It appears we cannot download V6 anymore? I’m sure it’s just an oversight, as the migration documentation from 7 still refers to 6 and the download links still work if you reverse engineer the URL: https://artifacts.rnd.mendix.com/modelers/Mendix-6.10.20-Setup.exe Also the Mendix Studio version on forum only goes to 6.10.16
Indeed Mendix gives only easy access to versions that are supported. And with the release of Mx9 Mx6 was deprecated. If you need an older version you still can get it through support.
Might not be an oversight. Today Mendix 9.1 has been released and Mendix apparently do not want to maintain too many major versions. But what minor and or patch-version do you need? Maybe someone can get you a copy of the installation files.