Basement Apartment & Zoning/Regulations

Hi, I am planning on purchasing a new property in the next 3 months. I want the property to have multiple units and have looked at duplexes-quadplexes, but are most likely going to settle on a house with a basement that we can turn into an apartment if it makes sense. My question is with turning an unfinished basement into an apartment or airbnb, is there anything I need to be aware of zoning and/or laws wise? Does the property need to be zoned as a multi unit property? I am looking at buying this property in Smyrna, Georgia in Cobb County which abuts Atlanta.  Thanks for your responses in advance!