Just in case you haven't got it working, or if anyone else encounters the same issue, I was able to resolve it fairly painlessly. Tannin discontinued the project when he was hired by the Nexus team to develop their new Vortex mod manager.
Mod Organizer 2 is a mod manager created by Tannin to support 64bit games like Skyrim Special Edition and Fallout 4 in addition to all the 32bit games MO1 already supported.
