What is my next step in the process to legalize it?

I'm interested in real estate in the Chicagoland area. 

I already know I am going to have to replace all of the hardwood floors and probably the subfloors. 

Second, the prospect stated on the application they lived in the property for 4 year, but the tenant rent ledger that was provided stated a move-in date of last year 2023 of October and for some reason doesn't have the name of the management company, and the ledger looked like it was created using Microsoft Word.

Welcome to the BiggerPockets community

I'm new to the real estate industry and the seller financing option is attractive because I see the option to purchase an investment property with a downpayment smaller than 20%. 

I do not want to re-zone the house to sfh, at some point if I want to close the access I want to be able to. 

Checking to see the cost of state and local taxes.

No one is covered here even though the insurance company will write the policy and take the premium.

For me, the only interest in going to the same place over and over is to own the place.