Computer Configuration > Administrative Templates > Microsoft Edge > Identity and sign-in
Both
HKLM\Software\Policies\Microsoft\Edge
Allow user to sign in to the same account in Microsoft Edge when a user signs in to a Microsoft website. If this policy is enabled or not configured, user are able to get sign in CTA or seamless sign in experience(if 'SeamlessWebToBrowserSignInEnabled' (Seamless Web To Browser Sign-in Enabled) is enabled) when user sign in on Microsoft website. If this policy is disabled, user will not get sign in CTA or seamless sign in experience when user sign in on Microsoft website.