your complete beginners incompetence aside
I have just hooked up my old gear, Macbook Pro, MOTU midi interface, Kenton converter and old Roland SBX10 sync box. Both the Kenton and the Roland have the same sync issues as the one I think you described. They start in sync, but after a while they wonder off.
If I understand all, the sync delay and such are there to compensate latency. But to be clear, this is not the problem here. It's the wondering off.
Warm regards,
Mark