They would be taking a huge leap of faith to try and pull off what you did.  

Also, focus on 2 years of job/income stability.Class D Properties:Cashflow vs Appreciation: Typically, all cashflow with zero or negative relative rent & value appreciationVacancy Est: 20%+ should be used to cover nonpayment, evictions & damages.Tenant Pool: majority will have FICO scores under 560, little to no good tradelines, lots of collections & chargeoffs, recent evictions.

You can always get a license and put it referral meaning you're not active, but are referring business to agents and collect a fee.

This next month (July 1st) is the first month collecting rent with them, but so far it's been very easy to use- and the monthly cost is right ($0!)

It means you need to make an honest, good faith effort to find a tenant in a reasonable time. 

Can anyone recommend a rent collection agency? 

Is there some sort of collection service where I give them all the information, they go after the tenants and just give me a cut of whatever they collect?

Seems kind of shady to me the way they are acting.I can't recommend these folks in good faith!!

Also, focus on 2 years of job/income stability.Class D Properties:Cashflow vs Appreciation: Typically, all cashflow with little, maybe even negative, relative rent & value appreciationVacancy Est: 20%+ should be used to cover nonpayment, evictions & damages.Tenant Pool: majority will have FICO scores under 560 (almost 30% probability of default), little to no good tradelines, lots of collections & chargeoffs, recent evictions.

I'm 51, been a corporate drone for most of my career, but made a leap of faith about two years ago and launched a small but growing tent and event rental business as a side gig.