Please read this topic: Krita 5.3/6.0 beta 1 released
That is the topic you should use to report any problems and also to read about problems that other people may be having and possible solutions.
Also, state which operating system you are using and which ‘package’ you use, e.g. Linux appimage or Windows installer or Windows portable .zip or macOS or Android variant.
Which link did you download it from?