How far does the door close? For some reason I was thinking it wouldn't
close at all.

There is a special oil made for garage doors, but it really only needs
to be put on the hinges & the rollers (if the rollers have ball
bearings) but light weight motor oil or 3-in-1 oil also works. WD-40 is
silicone based which gets sticky & the oil part evaporates very quickly
so it's not the best thing to use. Definitely do not use grease on the
rollers or door track. Grease will collect dust & dirt and may make the
matter worse.

If the door is closing part way & then reversing i would suspect the
door sections are rubbing hard against the jambs or molding. Simple
solution for that is to rub a candle along the entire inside edge of
the jamb/molding that the door touches as it closes. If you move the
molding the door won't seal when it's closed & if you try to plane it
down it will look like crap from outside once the door is closed.
Simply wax it once or twice a year & it should work fine.

Doordoc