The Exchange VSS writer to ensure that Exchange is in a good state for backup and will fully manage the snapshots during the backup for you. You do not need to do anything to the Exchange services.
You do need to make sure that the Exchange Databases and logs are always included in the same backup job.
After completing your first backup, check the system and application event logs. Check for any issues with the Exchange backup you should see VSS errors related to exchange.
STC