After installing any assets from Asset Store, i have 30 Standard Assets errors (30 per any asset installed).
I downloaded one asset now and… probably you’ll know the rest.
I believe that “pro only” in the errors mean that those functions are only available for Pro users.
Pro users have many bonuses and you can look at them here: Powerful 2D, 3D, VR, and AR software for cross-platform development of games and mobile apps.
Delete the asset as it has some pro only features.
And please, do not be so angry and don’t swear on the answers/forums. I’ve had many problems for my scripts and I haven’t gone mad looking for the solution.