Is there a specific document that I will need?

Here in NY if I wrote a cash for keys agreement, it would have to be filed in specific legal places with certain documents and notarized. 

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

Document the details of this deal as your sample deal.2.

If so what documents were used?

And of course, all the documents in the Roofstock diligence vault.

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

STR insurance provides broader coverage, including liability, property damage (even non-guest-related), and gaps Aircover might not cover.For damages caused by guests, document everything (photos, receipts, estimates) and file a claim through Airbnb.

But my realtor said they are going to do special assessment on this property and HOA runs badly. ( We requested HOA reserve document but no answers. ) We wanted to wait to see how special assessment going and close. 

You may also need to provide additional documentation, such as proof of income and employment, and may need to have a co-signer who is a U.S. citizen or permanent resident.In terms of buying with an LLC, it can be a good option for some foreign buyers, as it can provide additional liability protection and potentially offer tax benefits.