Are there WordPress user capabilities needed for the customizer?

I’m creating a theme for Themeforest and in their requirements they say that I should use the functions current_user_can to determine if the current user has certain capabilities. For me this would only have consequences for the customizer.

I have a PHP file with all the settings etc. in it. This file is loaded from the functions.php file, so I could use an if-condition to determine if the current user is allowed to edit the customizer.

But I don’t know if this is needed. Does WordPress itself take care of user capabilities in the customizer? Or isn’t this relevant at all, probably because every user can customize the site (it would seem a bit unlogical to me though)?

I searched on the internet, but I can’t really find helpful information about user roles and the customizer. Can anyone tell me how this works in WordPress and if I should do sth as a theme author?

Many thanks in advance!