Mine were blocked several times and I opened them until the jelly under was gone, then it doesn't matter.
It look almost similar to other candy crush games and specially the soda version.
As you are collecting the keys you need to keep the spaces open for the keys to drop out and at the same time be very careful not to clear the yellow candies on the left as they are unlocked as these will grow the frog as it moves up the conveyor.
Combine special candies with each other to spread more jellies.