It gets complicated!
If you have the Adobe Creative Cloud Desktop App still resident on your system, then Lr6 will install as a subscription version with a 30-day trial.
Before you install the 6.14 version from the link by @dj_paige I suggest you use the Cleaner Tool to wipe all vestiges of the Desktop App from your system CLEANER TOOL
Then you may also strike 'Activation' problems that only a chat with Adobe staff will result in an 'Activation Reset'. (Adobe limits activations for Lr6 to two.)
Regards. My System: Lr-Classic 12.3 Photoshop 24.5, ACR 15.3.1, Lightroom 6.3.1, Lr-iOS 8.0.8, Bridge 13.0.3, Windows-11.