No entitlements (tickets, rooms, FP+..) is added to a Magic Band, they are added to
MDE (My Disney Experience) profiles. The Magic band is just the physical key to your MDE.
Tickets can be purchased from any source like
UT and have nothing to do with getting magic bands. (Magic bands are the main way to unlock your room door, but you could ask for a card). With other vendors, you have to manually add tickets to the MDE profile.
To take advantage of the on-site 60 day FP+ window, you will need your room and tickets attached to your MDE profile before that 60 day window starts.