Hi, @Menta Elise
Thank you for posting in Microsoft Q&A forum.
This is because the CM client uses a computer certificate to communicate with the management point but when you are using a normal user you don’t have access to this certificate.
We can specify a certificate to use by using PowerShell as an admin and running the command Invoke-WebRequest.
$cert = Get-ChildItem -Path "cert:\LocalMachine\My\<ThumbprintOfCert>"
Invoke-WebRequest -Uri "https://<mp_server_name>/sms_mp/.sms_aut?mplist" -Certificate $cert
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