Using right alt/option

Hello,
I want to buy full Parallels license, but there's one crucial issue with trial I'm using right now. There's no possible way I can find to use right alt key to write Polish characters in Windows 10 VM.
Is there any solution to work it around. Left alt key works fine, but using right alt key to write local characters (eg. r.alt + o = ó, or r.alt + l = ł, r.alt + n = ń),
Can someone help me with this please, cause from it depends if I'll buy full license or not.

Thanks,
Piotr