there are a few ways to run a program as system user.
a. the easiest to use and test with it task scheduler.
create the task and run is as system user like this
you can run the tast via the gui of task scheduler or via command line
Using the OS (Windows 10 Pro x64 in my case) menu shortcuts it's possible to share a mounted drive via rclone+winfsp+nssm (the last for mounting as a service):
The only way I know how to do this is to run rclone under the SYSTEM account.
This can be done a few ways:
By running the script from task scheduler using SYSTEM as the account
By doing basically the same thing using NSSM (an alternative to task scheduler basically that has some nice extra functions for robustness).
By using a Microsoft tool-pack called "PStools" (google it). One of these tools (psexec) allows you to basically log into CMD as the SYSTEM user if you are already an administrator. From there you can just run rclone normally. This is really nice to have for testing and debugging but it's not exactly user-friendly for an every-day use case, so the 2 first options are probably better practical solutions.
The reason this is needed is (as I understand it) a limitation in how Windows handles user-spaces. Any virtual mounts created on a user-level will not be visible to the system - and it is the system that is invoked to enable network sharing among many other things, so it will be confused and not see the path you are trying to share. Anything the system does is visible to users however, so if that is where you run rclone it will all work as expected.