This feature allows for exhibitors to self-assign a booth number from your live floor plan at checkout and that booth will automatically be added to their order. If you approve that order, then the booth number will automatically have that Exhibitor assigned to it within the Live Floor Plan. You can always change their booth number, even after approving the order, via the Manage Live Floor Plan or selecting their 'space number' field located in their order summary.
How do I enable this feature?
First Proceed to the event wizard menu through Edit Showcase Page link next to your event.
Then navigate to the pricing tab and select "Add/Edit" under Event Spaces.
You will see the Event Space Edit page. Just turn on the switch for "Enable Inventory Tracking", and then you will see "Exhibitor Booth Purchase", which you can also set to Yes.
This will sync the Event Spaces that you have in this interface with your Live Floor Plan and enable the vendor to be able to select a booth to be assigned to at checkout instead of the other option which allows Exhibitors to select their 3 preferred spots.