Plutonium

4chanWizard

You're making this way harder than it has to be
Your error is because YOU installed/directed the launcher to broken files
There is no ownership verification or whatever like I explained with simple words: verify your game files in the Steam app, not on our forum

The game files you are using are broken and you fail to understand anything too so that's a you issue
If you simply downloaded the game from Steam and pointed the launcher to it you wouldn't have these issues

Usernames are case sensitive, make sure you're writing your name exactly as you have your name here.

For example 4chanwizard won't work, but 4chanWizard will.