@jcolideles @MaXi32 @Navigator
I had exactly the same problem. Everything activated, but no DNS Provider option under SSL Certificates.
I analyzed build script and there is dnsprovider.json copying procedure for ./build lego, however ./build letsencrypt executes ./build lego procedure only if lego is not installed yet.
Try to execute
restart directadmin and check then.
I will test this, I actually use my own script to add DNS record externally since version 1.5 because directadmin external DNS was not working before and the feature was in testing mode (maybe it is fully working now). I will test this feature again and let you know if it is working..