I would assume that all of the Bay Lake Tower rooms would have a balcony because a balcony is shown on the plans. If the plans on their website are correct, it looks like there will be a regular glass door in the living room of the 1 bedroom unit that opens out. The plan shows another door in the Master bedroom, which looks like a sliding door because a set of French doors would take too much space.
If that is correct, you could put something in front of the living room door from the outside that would prevent it from being opened. And, then put one of the sliding glass door items that other people mentioned to keep the Master bedroom door from being opened.
If you are in a studio, it looks like there will probably be just one door, a sliding glass door.
I would imagine BLT would have sliding glass doors similar to this picture of a 1 bedroom at SSR shows:
I could not find a picture of a single door, but OKW has a single door that opens out in the Master bedroom like the French door in this picture of a Boardwalk villa studio shows:
Here's a link to the DVC BLT website where you can look at a small map and a 360 tour.