Hello @민귀 박
Welcome to Microsoft Q&A Platform.
Can you check the reply from Evan Wang from the below thread and see if using a GPO works?
https://social.technet.microsoft.com/Forums/windowsserver/en-US/112c5363-3435-473e-8bf0-c01cd8cd7540/start-program-for-rdp-users-on-login-on-windows-server-2019?forum=winserverTS
I hope this helps!
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