I had the same problem on my Macbook Pro - OS Catalina 10.15.4. It seems to come from the "hosts" file.
1) Find the "hosts" file: Macintosh HD> private> etc> hosts
(These are hidden folders. You can find different ways to view your Mac's hidden folders and files on the internet. Personally, I use Onyx software.)
2) Copy and paste the "hosts" file on your desktop and open it with TextEdit.
3) There will be lines with the PreSonus mention preceded by an IP address. Delete these lines and only these. Save.
4) Copy and paste the new "hosts" file from your desktop into the folder: Macintosh HD> private> etc and replace the old one. Enter your administrator password and validate.
5) Open Studio One 4 and log in. It should work now.