Modding Skyrim is tough... sometimes.
Modding Skyrim is tough... sometimes.
You can start Skyrim via Steam, or if you have SKSE installed, launch it using NMM.
I work with the SKSE.exe file and its pinned icon on the taskbar.
I recommend installing Nexus Mod Manager. It's a great tool. You get control over mod loading sequence (important) and can turn mods on or off before starting the game directly from the manager.
The issue with your game download is identified by checking its load sequence, which helps determine the cause of the problem.