You are using ITMS 8.7.3 release in your environment and you are only using "Token" authentication (it is enabled per white paper describing how to setup ITMS with token-based authentication).
You have imported Windows 11 (24H2) extracted and zipped iso files, for example, in your SMP Console.
Now on the remote Package Server (PS), you see warning messages like:
"11/26/2024 9:53:36 AM","Failed to set security for 'C:\SMA custom location\Altiris Agent\Package Delivery{DC39252F-20FF-45D7-A82C-372FE42D0017}\cache\Windows 11 24H2 US OS iso Upgrade\sourceseplacementmanifests\microsoft-windows-appx-deployment-server\windows.miracastview_6.3.0.0_neutral_neutral_cw5n1h2txyewy.xml', error: The system cannot find the path specified (0x00000003)","Package Server Agent","AeXNSCPackageServer.dll","2120","Warnings"
You have verified that the exact xml file exists in your PS directory.
ITMS 8.7.3
Known issue. This is not about token authentication; This is about paths longer than 255 characters - security configuration fails for those.
Remote Package Server fails to process packages that have > 255 characters combined filename with "Failed to set security" error.
This issue has been fixed with our ITMS 8.8 Release.
For those with ITMS 8.7.3 release, refer to the pointfix available under KB 382575 "CUMULATIVE POST ITMS 8.7.3 POINT FIXES"