Password based login is disabled for snapuser user, so I do not think there is any need to change the default configuration.
The Groundplex has not been tested with an AD user, but it should work because it just needs to be a valid user account. Instead of snapuser, if the user wants to run with an existing AD user/group called aduser, then the steps would be
Add this entry in /etc/sysconfig/jcc, creating the file/folder if required
export SL_USER=aduser
Then restart JCC process and change ownership to aduser by doing
sudo /opt/snaplogic/bin/jcc.sh stop
sudo chown -R aduser:aduser /opt/snaplogic
sudo /opt/snaplogic/bin/jcc.sh start
