They get the sale and its not any harder than finding a home for a retail buyer. 

For example if a single family home rents for $1700 in your area.

For starters, I recommend to begin with a single family home or if you are looking to start locally, do house hacking. 

I have lumber liquidators, home Depot, Lowe's, and who knows what else near me (central CT).

This had nothing to do with economic or underwriting issues but was driven by covid and many workers beginning to work from home. 

Can’t house hack, we own a large home with lots of kids.

Central PA is only about an hour and half from my home and looking to STR near Hershey. 

If you can get a better deal on the home due to age its a fine and if you need financing banks do not judge year built. 

If I were to approach a seller of a $200k home, and they had a remaining mortgage of $100k, could I get a new bank financed loan for that $100k, and have the seller finance the remaining $100k of equity to me?   

I can also help you with your home/investment search.