Outlook app is prompting for the credentials inside the desktop. Every time open Outlook, it prompts for the user name and password

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If users experience issues where Outlook repeatedly prompts for a password after the AutoDiscover process fills in the required information, suggesting that the problem may also affect direct connections to Exchange Online.

Additionally, there may be interference from third-party applications,  which can block or disrupt the AutoDiscover process, causing Outlook to hang during authentication.

on the Master image set Registry and update machine catalog or configure GPO to appy the registry key: 

make sure "Shared Computer Activation" is set on the VDA

HKLM\SOFTWARE\Microsoft\Office\ClickToRun\Configuration\"SharedComputerLicensing" = String value (Reg_SZ) set to 1

HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Identity\"DisableADALatopWAMOverride"=DWORD:1

HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Identity\"DisableAADWAM"=DWORD:1

HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Identity\DisableMSAWAM=DWORD:1  

The Setting "ExcludeExplicitO365Endpoint" prevents Outlook from using the explicit Office 365 endpoint during AutoDiscover:

HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\AutoDiscover

Value Name: ExcludeExplicitO365Endpoint

Value Type: REG_DWORD

Value Data: 1

If UPM in use, please check Citrix Studio → Policies → Profile Management → Inclusion list – directories

AppData\Local\Microsoft\Office\16.0\Licensing

AppData\Local\Microsoft\Credentials

AppData\Roaming\Microsoft\Credentials

AppData\Roaming\Microsoft\Crypto

AppData\Roaming\Microsoft\Protect

AppData\Roaming\Microsoft\SystemCertificates

AppData\Local\Microsoft\Office

AppData\Local\Microsoft\IdentityCache

AppData\Local\Microsoft\OneAuth

AppData\Local\Microsoft\TokenBroker

Outlook app is prompting for the credentials (user name and password)