I have never seen a ride actually require a certain gear ratio - that is really odd, and I don't expect them to go around checking cassettes before they let you go. They typically just want people to be prepared and get as many to finish as they can.

That being said, it appears you have a mountain bike? It looks like you've got a 22 in front? I can only imagine that's a MTB, though I could not get the link to open. A 22 is WAY small, and well within the "requirement" for the ride, so you should be fine.

The smaller your front ring is and the larger your rear cassette cog is the "easier" gears you have, generally. Your 22 in front is smaller than the requirement, and you have a big juicy 32 in rear, so you're fine.

However, if this is a mountain bike, and you are doing the road century, I recommend putting slick tires on your bike for rolling resistance, quiet and comfort.