Use Scanners in Pool with Tags

When you select the Tags (Scanner Pool), select tags from the list of tags. If the tags associated with the scanner pool and the scan target match, the scan is launched. 

Tags Assignment to the Scanner Appliance

If you specify a tag that is not assigned to a scanner appliance, you will get an error, and your scan will not launch. Make sure all tags in your scan target are assigned to scanner appliances, or select a different scanner appliance option.

To assign the tags to the scanner appliance, in Vulnerability Management, go to Scans > Appliances, edit the scanner appliance, and select one or more tags for the appliance.