You can complete the Office 365 guided setup using the express configuration option, which automates some configuration steps.
After you create the Azure app that is needed for the Exchange Online app, the express configuration automatically creates one or more Exchange Online service accounts for the Azure app, and then syncs and authorizes the Azure app with Azure. The service accounts have the ApplicationImpersonation and View-Only Recipients permissions. The number of service accounts that are created depends on the whether your environment uses modern or basic authentication:
Modern authentication: The express configuration creates 1 service account.
The service account is used only for mailbox discovery and license computation, and you can remove the ApplicationImpersonation permission from the service account.
If you do not want to use Exchange Online service accounts, when you create the Exchange app using the guided setup, for Exchange Connection Settings, enter temporary values that you can delete after you create the app.
If you do not use Exchange Online service accounts, the following are true:
Licensed shared mailboxes are marked as user mailboxes.
Unlicensed user mailboxes are marked as shared mailboxes.
Mailboxes in an on-premises environment are marked as shared mailboxes.
Room mailboxes and equipment mailboxes are marked as shared mailboxes.
To back up and restore public folders, you must configure a service account that meets the following requirements:
Multi-factor authentication must be disabled for the service account.
The service account must be an online mailbox or a shared mailbox.
The service account must have owner permissions at the root level.
Basic authentication: For every 10,0000 mailboxes in the Exchange Online app, the express configuration creates 10 service accounts, and an additional service account for every additional 1,000 mailboxes. The maximum number of service accounts that are created is 25.
Verify That Ports Are Open
Verify that the required ports are open.
Disable Multi-Factor Authentication for the Global Administrator Account
To use the express configuration option, if multi-factor authentication is enabled for the global administrator account, you must disable it.
For more information, see "Turn on Modern authentication for your organization" and "Turn off legacy per-user MFA" in Use Conditional Access Policies in the Microsoft documentation.
After you complete the guided setup, you will enable multi-factor authentication again.
Go to the Office 365 Guided Setup
From the navigation pane, go to Guided setup.
The Welcome page appears.
On the Protect tab, click Office 365.
The Office 365 setup appears.
Create a Server Plan That You Can Use for Exchange Online
If you already have a server plan that you can use, you can skip this step.
On the Create server backup plan page, specify the settings for a server plan that you can use for the Exchange Online app.
Folders to back up
Add an Office 365 App for Exchange Online
On the Add Office 365 app page, specify the settings for the Exchange Online app that will contain the mailboxes that you want to back up.
Exchange connection settings
Enable Multi-Factor Authentication for the Global Administrator Account
If you disabled multi-factor authentication for the global administrator account, enable it again.
Verify the Connection to the Azure App
If you added an Azure app, under Exchange connection settings, click Verify Connection to verify the connection and update the status of the app.