Regardless of where you store the SAS Content Assessment software, you have to configure it to run on the SAS server you are assessing. Also the results of the assessment are stored in the same software folders. That means you need a copy of the Content Assessment software for each SAS server and each App server instance in your SAS installations.
Personally I find it a lot easier just to copy SCA to the same folder on the same drive on each of the SAS servers, as you need to configure each copy for that server. It's a lot less confusing that way. Yes you could run it off a network drive, but you still need a copy for each SAS server / SAS App instance to collect results.
To configure and run on a network drive, just remotely logon to your SAS server, open Windows Explorer, navigate to the network folder share where you have installed SCA and follow the SCA configuration and running instructions.
NB: Remember to create one SCA folder per server / app instance.