OpenTM2 is dead as a project. Many thanks will eternally go to Gerhard Queck, who developed it for most of his lifetime.
The 2 latest versions of the installer can be found here for download:
https://www.translate5.net/OpenTM2-1.5.1.1-Community-Edition.Setup.zip
https://www.translate5.net/OpenTM2-1.6.1-Community-Edition.Setup.zip
MittagQI (http://www.mittagqi.com) and the translate5 team (https://www.translate5.net) took over the responsibility of the successor t5memory.
With t5memory the source code was modernized, migrated to Linux, dockerized and turned into a headless translation memory engine. Also many bugs have been fixed and features will be added.
t5memory source code can be found here: https://github.com/translate5/t5memory Docker repos of t5memory can be found here: https://hub.docker.com/r/translate5/t5memory