Walkup check in jobs on VSys Live are just like those defined for the VSys Kiosk: they allow a volunteer to check in for a job for which she doesn't have an assignment, and that job comes with a description, location and rules which may be different from the job it's connected to. Walkup check in jobs are defined on a site-by-site basis and so each VSys Live site has its own walkup check in jobs. These in turn are distinct from those defined for the VSys Kiosk.
In VSys Live, they gain one additional property: Limit concurrent check ins. If this is checked, VSys Live will limit the number of people who can check in for this walkup check in job based on either the underlying job (in this case "Visitor Services/Boat tours") or the walkup check in job itself. When this is done by job, then the capacity limitations look for people checked in for this job regardless of what site (including the kiosk) they're checked into; when it's done by walkup check in job, only this site and this specific walkup check in job are counted. In either case, once a volunteer checks out, another volunteer can check in as long as the walkup check in job is still valid at that time.