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Citrix Discussions Xenapp 7.9: Wait for local session manager: “I have a Xenapp 7.9 environment on Windows 2012 R2.
Configurable Registry keys are located at HKEY_LOCAL_MACHINE\SOFTWARE\Citrix\Desktop Helper.
Add your non-administrator RDP users to this local group so they can RDP directly to the machine.
From CTX228128 What is the HKLM\Software\Citrix\Port ICA\Direct Access Users registry function: The HKLM\Software\Citrix\Port ICA\Direct Access Users registry key determines which Local group the VDA references to determine if a user should be allowed Unbrokered RDP access.
Citrix periodically releases Cumulative Updates for LTSR versions of VDA.
The latest Cumulative Update for 7.15 is CU1 (7.15.1000).