The credit score for all of them are decent. 

What documents do they require, what credit scores do they allow, how do they verify previous rental history, etc.?

No reason stated I had great credit score cash on hand excellent properties.

So far mostly people are telling me I'm probably stuck until their lease is over. meanwhile I also need to pay down my debt and improve credit score. 

In our opinion, Class C tenants have FICO scores from 550 to 600 - where their chance of default/nonpayment is 15-22%.

What minimum credit score?

I signed up for the paid version of Stessa through biggerpockets only to encounter flaws in their software, connection issues that have been ongoing for 10+ months, and basic feature missing that leave me dumbfounded. 

Many lenders and vendors rely on D&B scores to evaluate creditworthiness.2.

Take a look at the overall picture, i.e. credit score, debts etc.. to make a decision.

that we’ve learned in our 24 years, managing almost 700 doors across the Metro Detroit area, including almost 100 S8 leases:Class A Properties:Cashflow vs Appreciation: Typically, 3-5 years for positive cashflow, but you get highest relative rent & value appreciation.Vacancy Est: Historically 10%, 5% the more recent norm.Tenant Pool: Majority will have FICO scores of 680+ (roughly 5% probability of default), zero evictions in last 7 years.Class B Properties:Cashflow vs Appreciation: Typically, decent amount of relative rent & value appreciation.Vacancy Est: Historically 10%, 5% should be applied only if proper research done to support.Tenant Pool: Majority will have FICO scores of 620-680 (around 10% probability of default), some blemishes, but should have no evictions in last 5 yearsClass C Properties:Cashflow vs Appreciation: Typically, high cashflow and at the lower end of relative rent & value appreciation.