Some mistakes on Big Sur

macOS and Mac Apps

Hi friends,
I'm having some problems since I installed Big sur.
Firstly, when I try to connect to Mac app, a message appears saying impossible to connect, it happens sometimes and others, suppossedly, it allow me to do it, but when I try to download an app my password is required, I entered it and, although I know it's correct, an error appears.
Another thing is that when I try to change the voice that announce the hour aloud I can't.
Does anybody have the ssame or similar problems?
Can these problems be solved?
My computer is a Macbook air from 2017.
Thank you in advance.