It is really easy to get to the meeting point. From Cancun Hotel Zone you just have to take R-2 Bus to downtown (is $12.50 pesos per person) and ask the driver to get off at the Chedraui Supermarket in Tulum avenue.
*NOTE: Don't get confused with the one nearby Cocobongo in the Hotel Zone.
How long is the ride?
Depends of course on how far you are from downtown, could take from 15 to 40 minutes to get there, just ask to staff in your hotel about distance and timing. Remember to be at the meeting point at 7:00 p.m.
This is how meeting point looks like.
Chedraui supermarket will be on your right once you get off the bus, also you can see a shell fountain located on your left and a Office Depot in front of it.