without going too off topic, I discovered OOTP and baseball much later than FM, I find OOTP incredibly difficult to get into as there's so many games in the MLB season and so many different contract and roster requirements. I've read tons of stuff but never seem to retain enough info to get into.
Good luck with FM though, MLS is a notoriously unique league to play in, in FM terms, and starting unemployed with no coaching badges etc is pretty hard core.
FWIW I wouldn't worry about huge databases for now and simply start with the main leagues loaded and play a season or two as a big top division club to familiarise yourself. 👍