HOW TO UNLOCK ALL ATS MAPS ONLY FROM THE BASE GAME

Yeah, you can use it to collect achievements 'legally' without a tool such as Steam Achievement Manager (SAM).

This is how it's done

1. Download the latest version from https://mosbymods.de/ATS/
2. Locate your ATS game folder
3. Extract, copy & paste
4. Done

FAQ

Thanks to @Phys1q, best regards.
https://youtu.be/DHLjzLieydQ?si=iyHQlsCXVxCJ4A6G