Assuming you have Opus in Polish, that should be what the Prefs dialog asks the browser to open when clicking the "tools" link. If Opus is in English, change the polski to english (or en-gb for UK English).
The version number on the end shouldn't matter, but in my example it's what would happen when doing it from 13.20.3.
If that works when opening it manually, I'm not sure what could be going wrong. I'd suspect something outside Opus, since all the redirect URLs are opened in the same way. Maybe a proxy/firewall or similar doesn't like fileopendlgs being part of the URL for some reason, if it's coming from dopus.exe? Seems quite strange though.