How do I post multiple For Sale By Owner listings?

[Savannah Summers]

Hello, I’m new to real estate and currently finishing my Econ undergrad at the same time. I help manage properties and right now, I’m trying to help my partner get some of his properties listed and sold. I know that if I had my real estate license it would be much easier to help him, which is a goal. 

For now- Zillow's for sale by owner listing process will not work, I've been communicating with their help desk. I've since moved on to FSBO-online, however I can't check on the status of the posting, and you can only submit one property.

Are flat-fee MLS sites or otherwise free listing sites like Craigslist the only options? It seems that he has been able to list his properties pretty easily in the past and doesn't recommend Craigslist. Any suggestions and guidance is appreciated!