What I found amazing about all the videos is they all tell you
how to install addons but none of them explain how to activate them. I guess because they feel it is pretty simple to understand by simply reading the screen and using common sense.
The first thing is, log into one of your characters rather then remaining on the screen where you can choose one of your characters because it doesn't show the same information.
After you log in when you can not activate a mod because it is red and won't let you, it should be intuitive that you click the triangle by the name to expand it. Then you can see if the requirement is missing on not active. If a requirement is missing then you need to install that with minion. If it mentions a mod is not active then you need to activate the requirement. Some mods have other requirements to function properly so you may have to activate or install other requirements first.
Once you activate everything and nothing is in red log out and log back in and you should be fine. You can do this all at once from the character selection screen but mods will not show in red if you have not activated something for some reason. So just pay attention to what is and isn't checked. They all need to be checked most likely.