You did not point the launcher to the correct folder. Ensure your game is actually installed on your hard drive.
To minimize risks, always download from the Official TEK Launcher Releases page rather than third-party mirrors. Download Tek Launcher
: You can separately validate and update specific DLCs through the menu on the left. Version Rollback You did not point the launcher to the correct folder
Do not use random YouTube videos with a "Download Link in Description" unless the video is from a verified creator with a long history. Download Tek Launcher