Computer Configuration > Administrative Templates > Microsoft Edge > Password manager and protection
Both
HKLM\Software\Policies\Microsoft\Edge
Enable Microsoft Edge to save user passwords. The next time a user visits a site with a saved password, Microsoft Edge will enter the password automatically. If you enable or don't configure this policy, users can save and add their passwords in Microsoft Edge. If you disable this policy, users can't save and add new passwords, but they can still use previously saved passwords.