Are we allowed to rent a lane for lap swimming ? And is there a clock as well?

No renting. Yes clock. You can only do lap swim during the scheduled lap swim time. You can check their website to see the schedule

Lanes are first come first served, and you are required to share the lane with up to 3 other people. As noted above, only during scheduled lap swim times. If you chat with the front desk they are happy to share when lap swim is least attended, but still no guarantees...