How do I sign up to train sim and get some of the free MSTS add ons? I have tried to sign up but it is confusing.
Once you register they will send you an email with the authorization. After that, you have to keep trying to get a download slot unless you have a paid membership.
You should also look at the Maple Leaf Tracks forum (not run by MLT, but you can get there from them). They have some of the same locomotives, activites and rolling stock without the limited access (so far).
I should say some of the more recent uploads are also there.
Also be warned that a lot of the stuff on that site is dependent on having either Cascade Crossing, Rogers Pass, or another MLT product. The are still plenty that don’t though.