Could be anything and you’re unfortunately mostly alone with running OH on MacOS.
I wouldn’t even be sure there’s compiled packages of the snapshots available for Mac. Check out the logs.
Increase log level if that does not show enough (now as I understood you don’t get up to an accessible Karaf console, that’s a bit tricky and I’m not sure how it looks like on MacOS. On Linux there’s a file /var/lib/openhab2/etc/org.ops4j.pax.logging.cfg that you can edit), hopefully it’s the same on MacOS.