Microsoft encouraged customers to sign into a Microsoft account (with the same warning message) but Microsoft account sign-in is not necessary. Here’s Excel 2021 open with a worksheet and Word 2021 also open, ready to make a new document or work on an existing one. Editing files in Word, Excel or PowerPoint is quite possible without signing in. The second paragraph is wrong according to our tests. See Two ways to open a OneDrive document in Microsoft Office However, if you’re using the OneDrive app to sync files then you’ll still be able to work with OneDrive documents be opening them in the local OneDrive folder. Any cloud stored files should be saved (to the cloud or a local drive) before logging out. When you’re ready to edit files on this device, sign in to Office again. To complete the process, close all Office apps. Save any Office files that sync to the cloud (such as OneDrive) before you sign out. Signing out will remove your account from this and other Office apps. It says more about Microsoft’s desire to have all their customer logged into their system.

This is how the registry key will appear in Registry Editor after you set it.The ‘warning’ isn’t entirely accurate. 'DisableSupportDiagnostics'=dword:00000001 To turn off Contact Support set the policy in this article and below, Disable support diagnostics in Outlook.

To work around the issue, you can turn off Support Diagnostics, which turns off the option to submit an In App ticket using Help and then selecting Contact Support. The bug is related to how Outlook is authenticating for the diagnostics in some situations. Until the fix is available in your Office channel use the workaround below. To check what channels the fix is available in, please see the Update history for Microsoft 365 Apps (listed by date) page. This issue is fixed in Version 2303 Build 16227.20202 and higher. Use your work or school account instead.'

'You can't sign in here with a personal account. Or, you already have your account added in the Outlook Profile, but 'Need Password' is displayed on the Status Bar. When you attempt to sign in with your account you receive the error dialog below. You are prompted to sign into Outlook for your account and receive the error dialog below.

Microsoft outlook sign in