Have you been able to install other apps outside of the Play store before? Can you try some of the options in the below links?
https://www.geekinstructor.com/2019/03/fix-app-not-installed-error-android.html (Editing the setting in the Play store)
https://www.digitbin.com/app-not-installed-fix-error/ (Options 3, 6, and 7)