Hide “Try the New Outlook”

Regedit:

HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Options\General
DWORD: HideNewOutlookToggle
Value: 1

Source: https://answers.microsoft.com/en-us/outlook_com/forum/all/how-to-get-rid-of-new-tool-bar-saying-try-the-new/91cfddc8-a9b5-4195-9df2-7768d05501bd

Microsoft Office 365 Catalina

Download previous version installer compatible with Catalina

https://officecdn.microsoft.com/pr/C1297A47-86C4-4C1F-97FA-950631F94777/MacAutoupdate/Microsoft_Office_16.55.21111400_BusinessPro_Installer.pkg

Other Versions

https://docs.microsoft.com/en-us/officeupdates/update-history-office-for-mac#release-history-for-office-for-mac

Outlook Emails Blank May 2021

Close all office programs (outlook, word, excel, powerpoint).

Click Start

Type CMD

Command Prompt should be selected

Click Run as Administrator

Copy and paste this command:

“C:\Program Files\Common Files\microsoft shared\ClickToRun\officec2rclient.exe” /update user updatetoversion=16.0.13901.20462

Press enter.

Wait for office to install previous version.

When you see the Updates were installed screen you are good to go

Deactivate Office 365 Mac

https://support.microsoft.com/en-us/office/how-to-remove-office-license-files-on-a-mac-b032c0f6-a431-4dad-83a9-6b727c03b193

Also terminal:

defaults write com.microsoft.Word ResetOneAuthCreds -bool YES