Selvatica ziplines - link to book doesn't work?

AFAIK they closed down

I think the water parks are already closed. The issue isn't with the booking link. You can explore other options; I recently visited a different attraction in Cancún, Extreme Adventuring Cancún, and it was quite enjoyable. They have a variety of activities, including zip-lining and rope courses. You can also check out the options on Viator for other experiences.