Count character 'a' in first n characters of indefinitely repeating string s
Your getCount() method is a little difficult to read, on one long line like that, and way too complicated. s.count(_ == 'a') is both concise and efficient.

It's not clear why the number of s repetitions possible in n is called duplicate. It seems an odd choice for that variable name.

Your algorithm is sound, I just find it excessively verbose, especially for a language that prides itself on being both expressive and concise.

val sLen = s.length
s.count(_ == 'a') * (n/sLen) + s.take((n%sLen).toInt).count(_ == 'a')