AUM can’t receive transport on its own. I just got MIDI Link Sync (or MIDI Sync Link, can’t remember which) that acts as an Ableton Link bridge for this. I can now sync AUM to my Octatrack. You still need to do transport manually in AUM, though. You CAN use AUM to send sync and transport to your Modal, though.
If you have Audiobus 3, you can nest AUM inside of it with Link enabled and it should sync clock and transport. I don’t like doing it like that but it works. I just wish AUM would implement MIDI clock slave. I like it so much more than AB3.
The no transport thing in AUM is very annoying. I mailed the AUM guy but he doesn’t want to add responding to midi start/stop transport till he does adds support for AUM as midi clock slave.
I get that doing clock is non-trivial but just handling start stop would be neato.
If more people mail him about it maybe he’ll realise the issue affects a lot of people.
I’ve run in the same problem with AUM and external gear. It’s as @slicetwo said. There is no direct synchronizing to the outside world … but FYI … it works pretty straight forward with Audiobus 3. I loaded my sequencers and synhs in Audiobus 3 and everything works as wanted. External gear delivers the clock, starts, and stops the iPad sequencers. There wasn’t even a setup digging necessary.