It ships with an ApolloOS rom but there is a maprom feature that will put os 3.X rom into the core.
Since the Amiga situation has once again become a legal quagmire the kit ships with ApolloOS an Aros forked version to support 68K and the 68080 core.
IF you have purchased your own rom you can kindly flash it and use whatever flavor of os 3.X you wish.
Flashing new cores is done via a $10 USB flasher.