Fixed.

The example given in the description has a typo in the class name. It says "SimpleAssebmler" but it should be "SimpleAssembler".

and returns the amount of numbers that fulfill the requirements, and the largest number under limit

That's 13 in that case.

I honestly don't understand. 13 is prime so it can't be factored into other primes like 2 & 3. How can it be part of the answer?

I suggest you to read the description.

Surely this test case in python is incorrect since 13 is a prime number therefore cannot be factored into primes 2 and 3

primesL = [2,3]
limit = 200
test.assert_equals(count_find_num(primesL, limit), [13, 192])

char two_letters[2] = {a, b}; // << here's your problem

C strings are zero terminated. So allocate 3 chars and add a 0 at the end. Or better yet use string::susbtr.

You're not returning anything from your function.