In MATCHi you can find many activities at different venues that you can sign up for. It's up to each venue to decide what activities they want to have, and the rules around them. The activities can be found in MATCHi as long as the venues want. You pay that price that you can find under the activity, and the payment is being done during your booking of the activity.
The venue decides what cancellation rules apply to the activity occasion and if the occasion automatically cancels with a refund if there are too few participants.