I also have some capital to contribute.Could someone explain how syndications are typically structured, and how are people using Other People's Money (OPM) to build large portfolios with little to no money down?

If you want to build a large number of properties, get connected with local meetups. 

Start with one close to home where you can learn and build a team.

Focus on affordable markets, build a strong network, and continually educate yourself through books, podcasts, and deal analysis to steadily expand your portfolio.Good luck!

I'm currently adding all of my numbers for a 20-unit apartment building in for a test, and then I'll bring my other 90+ units.

It's a winning combination of direct access to industry experts coupled with building lasting relationships and get direct feedback on your strategies in small-group format.

As someone who's spent the past 20 years building software to ingest massive amounts of random data, the short answer is, it's really difficult to get accurate contact data.

Build a relationship with a banker from your home bank.

You are working a demanding corporate job but also want to build rentals on the side.

Reinvest profits, stay patient, and keep building toward replacing your income.