It's not possible to add the username and password to the mstsc.exe
.
But this should work:
# Create credentials
cmdkey /generic:"<servername>" /user:"<username>" /pass:"<password>"
# Connect MSTSC with servername and credentials created before
mstsc /v:<servername>
# Delete the credentials after MSTSC session is done
cmdkey /delete:TERMSRV/<servername>
(If the reply was helpful please don't forget to upvote and/or accept as answer, thank you)
Regards
Andreas Baumgarten