Having exact same issue, and trying to working tech support.
Here is what I just sent them in terms of what I did thinking the problem was at my end:
1. Uninstalled All Arturia Software
2. Rebooted machine
3. Disabled Modem firewall
4. Disabled Windows Firewall
5. Disabled Windows Defender
6. Re-logged into Windows
7. Deleted everything in #temp#
8. Verified no credentials saved in Windows Credential Manager
9. Ensured no registry entries for ASC
10. Downloaded ASC
11. Reinstalled ASC and ran as admin
12. Immediately after trying to login:
Nothing has worked so far.
Anybody have any luck?
Modified response at 8:51PST:
I cleaned the registry again, cleaned ProgramData as well, and with no trace of my credentials being saved, and after I open the program, just letting it sit without even attempting to put a username/pw in the fields, got the message "Can't connect to Arturia servers" - definately an Arturia issue!