In a quick test on RB5009 (arm64), I get a layer error (specifically, “error getting layer: resolving error” when downloading a layer). On RB1100Ahx4 (arm/v7), it imports and goes to start.
There is a Traefik container that works fine on same RB5009, so /container is enabled/working otherwise. You might want to try an older tag of HA instead of latest, dunno.
It should work since Mikrotik specifically documents how to set it up: https://help.mikrotik.com/docs/display/ROS/Container+-+HomeAssistant