By default, a new event starts out with 0 (zero) teams.

As soon as you go to Teams button in the team sections screen, it automatically creates team 1.

Add some teams. Add a few more teams than you think you need. You can delete them when the event starts. It is easy to add teams now in this screen and delete them later rather than add as each new team buys.

What I do.... is in a separate Tab, I go to Edit->Teams->Team names/Captain Names/Strat Overriders

In this new tab, note that the Bridgescore+ icon is red not blue. This means each time you enter data and then leave the text input window, the data is automatically saved, there is no Save button for this screen.

Try typing in some names. I normally announce that any PG13 names are acceptable, but nothing political. "Desperate Damsels", "Kicks Butt" etc. are allowed (by me). It gives the players a little fun in picking team names, but don't allow anything that may cause offense.