The event-level sync syncs all the contacts currently part of the event you are viewing. Please start by clicking into the events tab on the left, and then select the event you would like to sync contacts from. From there, (1) click the menu in the top right corner, then (2) click "Sync Event and Contacts with Wealthbox" in the menu.
After you click "Sync Event and Contacts with Wealthbox" in the menu, a popup will appear. From there, you have the option to select tags to apply to the contacts you are about to sync into Wealthbox. After you are done selecting the tags you would like to use, you will need to click "Start Sync with Wealthbox." Please note that you don't have to select any tags if you prefer not to.
After clicking the "Start Sync with Wealthbox" button, all the contacts from that event will sync into Wealthbox.