SkyrimTogehter.exe, is placed at:
C:\Modding\MO2\mods\Skyrim Together Reborn\SkyrimTogetherReborn
C:\Program Files (x86)\Steam\steamapps\common\Skyrim Special Edition\Data\SkyrimTogetherReborn
C:\Modding\MO2\overwriteis empty. If not, delete everything inside the folder, and start over.
skse64_loader.exe, loading your most recent savegame, and then exiting the game. Return to MO2 or VMM, and launch the game using the custom Skyrim Together Reborn launcher; it should now work. If you don't use SKSE, then try and launch SkyrimSE normally through Steam.