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##Seriously , 36 bytes

2╤R`;;3@%Y"Fizz"*)5@%Y"Buzz"*(+;I`Mi

Explanation:

2╤ push the value 10**2 (100)
R pop a: push range(1,a+1)
` start function literal
 ;; duplicate the top of the stack twice
 3 push the value 3
 @ swap the top 2 values
 % pop a,b: push a%b
 Y pop a: push 1 if a==0, else 0
 "Fizz" push the string "Fizz"
 * pop a,b: push a*b (in this case, "Fizz" repeated b times)
 ) rotate the stack right by one ([a,b,c] -> [c,a,b])
 5@%Y"Buzz"* Do the same thing as above, but with divisibility testing for 5 and using "Buzz"
 ( rotate the stack left by one
 + pop a,b: push a+b (string concatenation here)
 ; dupe top of stack
 I pop a,b,c: push b if a is truthy, else c (here, a and b are the same string, either "", "Fizz", "Buzz", or "FizzBuzz", and c is the original integer)
` end function literal
M pop f,[a]: using each element of [a] as a temporary stack, evaluate f, and push the result
i flatten [a] (push each value in [a] to the stack, starting from the end to preserve order)

Try it online.

Seriously , 36 bytes

2╤R`;;3@%Y"Fizz"*)5@%Y"Buzz"*(+;I`Mi

Explanation:

2╤ push the value 10**2 (100)
R pop a: push range(1,a+1)
` start function literal
 ;; duplicate the top of the stack twice
 3 push the value 3
 @ swap the top 2 values
 % pop a,b: push a%b
 Y pop a: push 1 if a==0, else 0
 "Fizz" push the string "Fizz"
 * pop a,b: push a*b (in this case, "Fizz" repeated b times)
 ) rotate the stack right by one ([a,b,c] -> [c,a,b])
 5@%Y"Buzz"* Do the same thing as above, but with divisibility testing for 5 and using "Buzz"
 ( rotate the stack left by one
 + pop a,b: push a+b (string concatenation here)
 ; dupe top of stack
 I pop a,b,c: push b if a is truthy, else c (here, a and b are the same string, either "", "Fizz", "Buzz", or "FizzBuzz", and c is the original integer)
` end function literal
M pop f,[a]: using each element of [a] as a temporary stack, evaluate f, and push the result
i flatten [a] (push each value in [a] to the stack, starting from the end to preserve order)

Try it online.

##Seriously, 36 bytes

2╤R`;;3@%Y"Fizz"*)5@%Y"Buzz"*(+;I`Mi

Explanation:

2╤ push the value 10**2 (100)
R pop a: push range(1,a+1)
` start function literal
 ;; duplicate the top of the stack twice
 3 push the value 3
 @ swap the top 2 values
 % pop a,b: push a%b
 Y pop a: push 1 if a==0, else 0
 "Fizz" push the string "Fizz"
 * pop a,b: push a*b (in this case, "Fizz" repeated b times)
 ) rotate the stack right by one ([a,b,c] -> [c,a,b])
 5@%Y"Buzz"* Do the same thing as above, but with divisibility testing for 5 and using "Buzz"
 ( rotate the stack left by one
 + pop a,b: push a+b (string concatenation here)
 ; dupe top of stack
 I pop a,b,c: push b if a is truthy, else c (here, a and b are the same string, either "", "Fizz", "Buzz", or "FizzBuzz", and c is the original integer)
` end function literal
M pop f,[a]: using each element of [a] as a temporary stack, evaluate f, and push the result
i flatten [a] (push each value in [a] to the stack, starting from the end to preserve order)

Try it online.

##Seriously, 36 bytes

2╤R`;;3@%Y"Fizz"*)5@%Y"Buzz"*(+;I`Mi

Explanation:

2╤ push the value 10**2 (100)
R pop a: push range(1,a+1)
` start function literal
 ;; duplicate the top of the stack twice
 3 push the value 3
 @ swap the top 2 values
 % pop a,b: push a%b
 Y pop a: push 1 if a==0, else 0
 "Fizz" push the string "Fizz"
 * pop a,b: push a*b (in this case, "Fizz" repeated b times)
 ) rotate the stack right by one ([a,b,c] -> [c,a,b])
 5@%Y"Buzz"* Do the same thing as above, but with divisibility testing for 5 and using "Buzz"
 ( rotate the stack left by one
 + pop a,b: push a+b (string concatenation here)
 ; dupe top of stack
 I pop a,b,c: push b if a is truthy, else c (here, a and b are the same string, either "", "Fizz", "Buzz", or "FizzBuzz", and c is the original integer)
` end function literal
M pop f,[a]: using each element of [a] as a temporary stack, evaluate f, and push the result
i flatten [a] (push each value in [a] to the stack, starting from the end to preserve order)

Try it online.

##Seriously, 36 bytes

2╤R`;;3@%Y"Fizz"*)5@%Y"Buzz"*(+;I`Mi

Explanation:

2╤ push the value 10**2 (100)
R pop a: push range(1,a+1)
` start function literal
 ;; duplicate the top of the stack twice
 3 push the value 3
 @ swap the top 2 values
 % pop a,b: push a%b
 Y pop a: push 1 if a==0, else 0
 "Fizz" push the string "Fizz"
 * pop a,b: push a*b (in this case, "Fizz" repeated b times)
 ) rotate the stack right by one ([a,b,c] -> [c,a,b])
 5@%Y"Buzz"* Do the same thing as above, but with divisibility testing for 5 and using "Buzz"
 ( rotate the stack left by one
 + pop a,b: push a+b (string concatenation here)
 ; dupe top of stack
 I pop a,b,c: push b if a is truthy, else c (here, a and b are the same string, either "", "Fizz", "Buzz", or "FizzBuzz", and c is the original integer)
` end function literal
M pop f,[a]: using each element of [a] as a temporary stack, evaluate f, and push the result
i flatten [a] (push each value in [a] to the stack, starting from the end to preserve order)

Try it online.

##Seriously, 36 bytes

2╤R`;;3@%Y"Fizz"*)5@%Y"Buzz"*(+;I`Mi

Explanation:

2╤ push the value 10**2 (100)
R pop a: push range(1,a+1)
` start function literal
 ;; duplicate the top of the stack twice
 3 push the value 3
 @ swap the top 2 values
 % pop a,b: push a%b
 Y pop a: push 1 if a==0, else 0
 "Fizz" push the string "Fizz"
 * pop a,b: push a*b (in this case, "Fizz" repeated b times)
 ) rotate the stack right by one ([a,b,c] -> [c,a,b])
 5@%Y"Buzz"* Do the same thing as above, but with divisibility testing for 5 and using "Buzz"
 ( rotate the stack left by one
 + pop a,b: push a+b (string concatenation here)
 ; dupe top of stack
 I pop a,b,c: push b if a is truthy, else c (here, a and b are the same string, either "", "Fizz", "Buzz", or "FizzBuzz", and c is the original integer)
` end function literal
M pop f,[a]: using each element of [a] as a temporary stack, evaluate f, and push the result
i flatten [a] (push each value in [a] to the stack, starting from the end to preserve order)

Try it online.