In order for network shares to be mapped into drives and accessible within Windows services, you need to login as the NT AUTHORITY\SYSTEM account.
To do this, download the Sysinternals Suite from Microsoft, and unzip it to a directory, say C:\TEMP
The following steps assume that you've unzipped SysInternals to C:\TEMP and all the executables are there.
If you need to remove it,
How to free more space on your home drive by redirecting the location for SDKs in RAD Studio