I couldn't get it to work before long ago, even though I was in fact doing everything right. I actually avoided using it for so long because it just wouldn't work for me. But recently, it did finally work for me. I don't know why. I did nothing different. Now, mods for that do finally have an effect on my game. Well, except the unofficial patches, which still don't work. And I do follow the instructions very carefully.
Of course, even if you can get it to work its still a garbage program. Downloads ramdomly freeze on you, and the thing can't handle files above a certain size. Luckily though, if a mod is big enough to not be installable with the mod manager the mod maker will at least warn you and tell you how to do a manual install; I had to do manual installs for immersive armors and weapons, and those mods do appear to be working. Well the armor one at least, haven't gotten far enough to see any new weapons yet. I have noticed a minor bug with ulfric: at the beginning when he's gagged, he didn't have the gag on his face this time. I was also surprised that both he and ralof were wearing new armors, along with general tulius and hadvar. I'm guessing the new armor on Ulfric is what's causing the bug. No matter. Not like its game-breaking.
And I can apparently disable my current food mod in the [censored] mod manager, so that helps I guess. Hmm, now that I think about it, maybe I can use my current food mod in tandem with realistic needs and diseases. How can I do that??? The food mod I have now is eat drink sleep bathe. The last feature, which requires you to bathe, I can probably still use. I can disable the other 3 features and use the ones from RN&D instead perhaps. As long as I don't use the other 3 features of my current mod I think I'll be fine. And yes, the mod is disabled by default when you start a new game. You have to manually enable it once you start a game. Hunterborn works the same way, I just found out.
And another thing I've noticed: now that I've started a new game, my frostfall meters finally display. Before they wouldn't show no matter what my settings were. That's handy. Now I don't have to sit there and press V constantly just to check the weather and my current temperature.
edit: opted to just disable my old food mod. The bathing thing honestly was kind of a nuisance. You can take food, water, and shelter with you, but not a bath. I mean, I had to install another mod just so I could take a bath in places other than rivers. So yeah, that's gone, along with the 'showers in inns' mod. Kinda thinking I had too many mods active anyway. I hear there's a limit to how many you should have at once, but I don't know what that limit is. Pretty much have all the mods active now that I want anyway. Kinda iffy about this deadly dragons thing though. Not sure what I'm getting myself into. All I know is while trying to escape helgen, I got a brief taste of the mod. I got knocked down while running through a building, which obviously doesn't normally happen. I guess alduin landed nearby outside or something. Thankfully I'll be playing an archer character this game. And hopefully he'll get past level 20.