@patologia21 Sure thing. The root of it seems to be needing to give Opera "permission to send encrypted data over the network/firewall". Unfortunately I don't know the step by step manual steps on giving applications network permissions, and i was going out of my hair figuring out the root cause. But the prompt that eventually did come up was specifically that quoted wording.
The only way i got it to work is the following, and im listing just to give you the exact steps that triggered the permissions request. I had Opera set as main browser, although everytime it would start going white and crashing i would need to uninstall with all user settings and then reinstall. So do this on a new install of Opera and make sure its set to default browser in your PC's settings.
The next thing i did was open a freshly installed Adobe Creative Cloud and when it asked for my adobe log in, i chose "sign in with Google Account." This is what opened a new session in Opera for the Adobe website and triggered the permissions request, all while linked from the Creative Cloud application.
It may be possible to do this with any linked sign-on prompt from an application while Opera is set as your browser, but the Adobe programs are your best bet imo because they all require a sign in and all accept Google linked accounts as alternative sign-in methods.