Do we have to Reserve the screen cabins in advance? And can we just go and paid wherever we want there at the moment or we have to make everything before we go?

It is not required to make a reservation, but it is a popular park and can fill up weeks in advance.

Always best to reserve. Go online that way you you can check for availability and make that reservation. But you have to plan ahead 3 or 4 weeks this time of year they fill up fast.

We had no luck in March driving up & requesting a campsite. The park was completely booked up well in advance. Best to call ahead.

Best to reserve in advance especially on holiday weekends.

You should reserve online as they will be sold out by then

I would highly recommend making the reservation online or by phone. The cabins seem to be filled up most of the time.