First of all, why don’t you use the F-Droid client as expected? You’ll get updates notifications and faster everything. The website is updater later, but Aard2 has been build already: https://f-droid.org/wiki/page/itkach.aard2/lastbuild and you can install it.
I cannot confirm that there was a aard2 web page all the time which disappeared, but aard2 has been on F-Droid for years. I installed it from there via client a long time ago.
Recently I noticed only by accident that a new version is available by looking at the latest tab. There was no update notification and an update wasn’t possible. I had to deinstall the previous and reinstall the new version. So something went wrong with aard2, whatsoever.
@critdroid , you are wrong. Aard2 hasn’t been in F-Droid. You used the version from Google play market or from the github (three same apks). I did the same