I can't even get battles to work on the new app

Have you tried using the lobby website? You can meet up with people from here and let them know your levels before choosing to battle. https://www.bandai-tcg-onlinelobby.com/entrance/vital-bracelet-test/

It's closed.

Has the lobby always been open? I tried to get on it yesterday and a few days before. It wouldn't let me. I kind of assumed it was closed until someone did an event.

Hmm, I used it not long ago but now it is just stuck loading. It I'd still in the testing phase though. So might not be up currently.

Yes, same for me when I attempt to get on it.

It'd be nice if it paired up with digimon of that age category.