Hi Hesaw,
1.65 is the current version of Magma which is only verified in Squeak 5.3 at this time. 6.0 is not supported yet. The good news is, its stability in 5.3 is very good (I use it heavily). I just verified the SqueakMap entry is working there (after fixing a glitch, sorry). I keep it maintained and working there for now until I can take on the upgrade project.
I believe that the github project was just an experiment that was abandoned. All the official code for Magma is hosted on SqueakSource.
Regards,
Chris