I do digitone keys to powered hub with other stuff (interface) to CCK to iPad. DNK sending sync. Using this app, generate Ableton Link clock from incoming digitone usb midi clock. Set AUM to use Ableton link. It still requires starting the AUM transport, and I think that’s because the app doesn’t send any position info, or perhaps camemout before Link included start/stop, but in any case, it’s the best solution I’ve found so far.
At the same time I sync DT to DNK via 5 pin, and sometimes also sync the BSP and/or TD-3 via MIDI out over USB in AUM. DNK’s 4 MIDI tracks can sequence AUv3s in AUM; add a USB cable for the digitakt to use its 8 MIDI tracks in AUM. Or the DT/DNS MIDI tracks over 5 pin could be additional LFOs. Or a AUV3 MIDI FX could add extra modulation to either. All easily set up in AUM, which btw, as of the last update, AUM does a much better job remember connections even if they are missing. Was a very nice detail.
Hope that works for you! I can’t see the apps current price but I think it’s only a few bucks, and for a 5 star app that single handedly fixes such a huge omission in most iOS hosts (even those I own that do support slaving to external midi each still have their own issues…) is a steal if you ask me. I recommend it every time I see this asked, which is so much more often recently I need to save a boiler plate or just drop the f’ing link already…