It does need to be listed as a condo, if this is the legal description of the property. Even if it is a site condo and you own all of it, including the roof and walls, the land ownership is not the same as single-family home and you cannot call it that for legal reason's. Also, when the person buying it is getting a loan, the lender will need to know that it is a site condo and not a single-family home as there are different types of loans for these.
If you are not a realtor yourself, I would suggest getting one to list it properly for you as well as promote it. There should be no reason that you cannot sell it quickly in the Austin market.