When you launch the VSP app for the first time, it will ask you and the volunteers for your Organization ID. This is the same as the Organization Web Identifier you set up when you first installed VSP. You can see what this is by clicking on the Subscription pane inside of VSP and you will see the Organization Web Identifier listed here.

For your convenience there is now a token in VSP to share this with your volunteers (and that token is included in the email template that lets the volunteers know a new app is available). You can use this token in the Web Terminal or in other emails you send to help communicate that ID. Click on the Token menu in the Announcements pane or in the Web Terminal pane, then drop-down to the Web Terminal section and select the "OrganizationWebIdentifier" token to add this token.