Unable to download Appian 16.2 or earlier

I am trying to download Appian 16.2 through forum, but am receiving the following error:

{"error":"APNX-1-0000-000","message":"User Does Not Have Rights to Perform this Operation","title":"An Error Has Occurred"}

I am able to download 16.3, 17.1, and 17.2 with no issues, but it looks like I am getting the error on anything before 16.3 (tested all the way to 7.10). Is anyone else having issues when attempting to download older versions? Thanks!