UPDATE 23RD NOV 2020: Respawn appears to be sorting out Titanfall's rough launch on Steam.
Late on Sunday the developers issued an audio issue patch, which fixes the awful audio issues the game had at launch. I've tested Titanfall on Steam this morning and confirm the audio is now as it should be. "Thanks for all your patience," reads a note.
Meanwhile, while some are still reporting matchmaking issues, I've found the game relatively stable since Sunday, and I've been able to complete the training. It looks like Respawn is getting on top of Titanfall's issues, and its "Mostly Negative" Steam user review rating has improved to "Mixed".