There is the possibility if you are experiencing difficulty with the time needed for the paint to dry, that too much paint has been applied. If this is the case, the dry time may take longer than overnight. The consistency of the material is somewhat of a "fruit roll up" and is to be expected, as part of the project is also a window cling and the flexibility is required. Due to heat and humidity, dry times may vary as well.
If you have difficulty removing the cling from the sheet and you see that it is stretching as you are pulling it off, work around the edges by gently pulling it up until you can pull the entire cling off of the sheet.