Casper BL

Is this a statement or a question?

Put it in another folder or start as admin

Nothing, use whichever version you want as long as it works for you.

Go to settings and download a new game list https://i.imgur.com/YRdJrRA.png

You can add the ID to the app list manually and try if that works

Extract ALL the files from the rar file.

@hackb0y SingleBoostr or HourBoostr? What version? When does this occur exactly?

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What is the error?

Buy or contact Steam support to recover your old accounts. Second option won't work unless you originally owned the account.