Are you sure that it is the first time you install SNAP?
The installer checks if certain directories exist and then shows this dialog.
The directories in question are <USER_HOME>\AppData\Roaming\SNAP
That’s the SNAP-internal directory <USER_HOME>/.snap
That’s the one with the user data.
First time i hear about that service.
But concerning your problem the volume really doesn’t matter. Only complexity of geometry and frequency of your projects. A good pc can be built to handle these projects for under 2k€