Reason why MO2 isn’t the “main mod manager” is that it was made for Bethesda games. MO2 is now an open project in the hands of the community. But Tannin discontinued the project when he was hired by the Nexus team to develop their new Vortex mod manager. Mod Organizer 2 was developed by Tannin to support 64bit games like Skyrim Special Edition and Fallout 4 in addition to all the 32bit games MO1 already supported. It's designed by Tannin, the creator of Mod Organizer, taking the lessons learnt during the development of MO and Nexus Mod Manager to provide the most powerful and intuitive modding experience available. Vortex is the new, modern mod manager from Nexus Mods. The current version of NMM is maintained by DuskDweller and Squidbox on GitHub. The last official version of NMM was 0.65.2. It was declared End-of-Line and no longer supported in December 2016. Nexus Mod Manager (NMM) was the in-house modding solution used by Nexus Mods between 20. In general, there are currently 3 popular MOD management tools: MO (Mod Manager), Nexus Mod Manager, and Vortex. But to install MODs more easily and smoothly, you may need a MOD manager tool. Some people may like to install MODs into games.

Introduction to Mod Organizer 2, Vortex, and NMM

Introduction to Mod Organizer 2, Vortex, and NMM.

Mod organizer not connecting to nexus