When you try to push agent to a non-domain machine (e.g, to use it as a VDI Template), you are prompted for administrator credentials. You try to login using not built-in Administrator account and error "Current credentials used on this system do not allow remote installation" is thrown:
At the same time in the Event Viewer of the affected machine you can see that the credentials are valid and logon was successful:
If you try to access default system network share like C$ in Windows Explorer, access is denied.
By default Admin Approval Mode is enabled for non built-in administrator accounts and prevents you from accessing system network shares.
You need to disable Admin Approval Mode on the affected machine. To do it, please launch Control panel, proceed to System and security → Administrative tools and open Local security Policy. Proceed to Local Policies → Security Options, open "User Account Control: Run all administrators in Admin Approval Mode" and switch its value to "Disabled":
Then press OK, restart the machine and repeat the push installation.