Glacier entry ticket

So we just got an entry ticket for glacierand its almost 5pm. We got it for Aug 14th was trying g for the 15th but was sold out at 10:01 EST. But I noticed the 14th still had 51 tickets available so grabbed one. So this is my question we r going to try to get a spot at Apgar campground. So let's say we get a spot sometime in that 7 days. So do we only have those days thst my ticket is good for to camp or once we have a site in the park we can stay. So confused ??