The HOA was created as part of a declaration of covenants which were recorded with with the State and parish when the subdivision was planned and developed.  By accepting your deed, you are accepting the terms of the “indenture and/or restrictions” as they were filed and automatically become a "Member" of that Association.

It is not required by any law that these indentures (restrictions) be provided to you by anybody including the realtor or closing company as it is considered public record and, unfortunately, charges you with finding them.
It is required, however, to be disclosed by the seller prior to purchase that a subdivision with assessment fees does exist.
 Years ago we installed the sign on our entrance road that states "Deed Restricted Community" to assist in that notification.

Learn about the Louisiana Homeowners Association Act by reviewing Louisiana Revised Statute Title 9 Section 1141 from the Louisiana State Legislators website.