Once the alert has been designed accordingly, and once it has been activated it will be pushed onto node all nodes that match the filter in the rule.
This will be performed at the next synchronization that takes place every 30 seconds by default.
To check if the alert has been properly pushed on the node you can lstalert.exe
Hint; Synchronization is a process where the nodes sends all information he has received back to UVMS to check if they uptodate (The node list, the security data , the alert rules it has received). Every 180 seconds a full synchroization takes place where UVMS sends all the current data to the node.