Thanks John - Booking Stack doesn’t have quantities as yet. So it can’t handle 5 students book a workshop in that example.
This is something we are looking to add at some point in a future update.
In the meantime you could take the name and email and then follow up with payment after you have received 5 orders? Then send a link to the payment page to “complete the booking”.
It sort-of works. If the un-bookable slots were invisible rather than greyed out, it would look a lot better. Even with one hour slots rather than the one minute slots I first suggested, there are 19 unwanted, greyed-out slots showing. Maybe I have missed a trick!