So you just used magic bands? If they mail tickets you also have hard tickets which you need if you don't have bands.
Yes, we just linked the ticket codes in the email to our MDE profiles and scanned our Magic Bands at the gate. No hard tickets.
I'm there again at the end of the month and while I'm now an AP holder, my friend used UT for her ticket - this is what the email says:
"Don't forget: You may add this E-Ticket to your MagicBand and go straight to the gate and onto the rides. If you do not have a MagicBand, you must exchange this E-Ticket at will call/guest relations or a sales location (ticket booth) for a RF-enabled ticket before admission. You may link this E-Ticket to My Disney Experience for FastPass+ reservations before will call exchange."
So looks like as long as you have use of a Magic Band, you just link and go. If you don't, then
@JourneysEnd is correct, you'd be able to choose FP beforehand online but would need to obtain a hard ticket from will call before entering the park.
I am the overly paranoid who likes to carry confirmation printouts along with hard tickets or whatever else I've been given in case something doesn't work, but I will say that I have used UT dozens of times, and never had a linking issue. They are my go-to to recommend to friends and family traveling and those that have used it have also never had an issue.
Whether you receive a hard ticket via snail mail or a ticket code through email, the linking process to your MDE account is the same. It basically comes down to how fast you need your tickets - if you have time to receive them through snail mail, then by all means. If not, use the email option.