Using classic Outlook for Windows in business environments
"First, go to Windows Settings (press Win + I ), > Windows Update > Advanced Settings and turn on the ''Receive updates for other Microsoft Products'' after that start Windows Update and wait for Windows to get the updates and restart your computer.
Then open regedit with administrator account (windows search > regedit > right click > run as administrator), then follow the path
Computer\HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Identity
if there is a EnableADAL Dword Value change it's value to 1, if there is not, create a new ''DWORD (32-Bit) Value'' and name it ''EnableADAL'' without quotes. Double click it and choose Hexadecimal as base, change its value to 1. Close regedit, close Outlook and restart your computer. When your computer opens try to get windows updates and open your Outlook again. Maybe this solution helps.
PS: In regedit path ''16.0'' maybe different in your computer, like ''15.0'', select the path which includes Common and Identity in it."
Has anyone tried this Registry modification suggestion from Süleyman? If so, does Outlook 2019 still ask for your outlook.com email account password sometimes? Wanted to get some feedback from someone who tried it before doing it on my end.