These errors has no effect on gameplay and has nothing to do with USK, because they appear in Photon scripts, so just ignore them.
Some characters have an incorrectly assigned hips bone and the character controller does not correctly calculate the floor height.
So the best solution is to open the avatar editor and set the correct bone there:
After importing the project, you may see red errors: no big deal, all those errors are standard Unity import errors and they can be cleared up by clicking the "Clear" button.
To solve any issue with Package Manager set the Scripting Runtime Version to .Net 4.x in the Project Settings
or try to reset Packages by pressing [Help -> Reset Packages to defaults]
Open the Mobile Input menu by pressing [Edit -> USK Project Settings -> UI] and set the range there: