Hi Giuseppe,
I am also facing this issue with my university credentials. The “Sign In” window gets stuck after typing in the email address. The "Next" button in the bottom right corner of the window becomes disabled, and an unresponsive blank window appears in the task bar.
I found a work around for this issue by maximizing the blank window. The blank window becomes active, and I can input my SSO credentials now. In case this window is still unresponsive, I close the window, and the “Sign In” window now prompts me continue to sign-in using a one-time password. You can access the one-time password on your PC in the following link:
I hope this helps resolve your issue.