Setup Single Sign On with Azure AD in your Secured Signing Membership
You need an enterprise account to integrate secured signing.
Login to the Enterprise Portal and go to "Memberships".
Select the membership that requires single sign on with Azure AD.
Click "Single Sign On" tab.
Tick "Enable Single Sign On Azure Active Directory" checkbox.
Click "SAVE SETTINGS" button.

Then, all users in that membership will use Azure AD to login.
Activate user account
Once new user account created for that membership (Azure AD login) through Enterprise Portal, the user will receive an activation email,
click "Click to Activate" button in the email. Then in the activation page, you just need to click "Activate" button (the email address already popuped),
then, it will redirect you to Azure AD, you need to input your Azure AD password for authentication, after that, it will redirect you back to our website with logined status.

Join an Existing Secured Signing Account to a Membership with Azure AD Single Sign On enabled
For an existing user, he/she can join a membership by adding the membership code to the "My Account" -> "My Details" page, put Membership Code and click "Join Membership"

Initial Login with Single Sign On (Azure AD)
Once single sign on (Azure AD) is enabled, the first time each user accesses Secured Signing they will need to input their email to login. A password for this case is not required.

The system will check if Single Sign On (Azure AD) is enabled for this user. If so, it will redirect to Azure AD login page. Then the user input his/her organizational logon credential to login with Azure AD server. The user can check the option to "Remember my email" to login with Azure AD next time.
Once the user has logged in with Azure AD successfully, the user will be redirected to Secured Signing.