I just bought a Synergy Severene 5.4 sail. The party that I bought it from never used it. I cannot get the mast into the sail without the sail binding. I've watched many videos as to the proper method for sliding the mast into the sleeve. With every single method the sail binded. I'm now wondering if the mast that I have is the correct one. The mast doesn't specify a specific size but I don't imagine that any of them do. Any ideas or recommendations?

The Synergy rig is designed to be easy for beginners so each sail has its own mast of fixed length.
Did you get the mast too, or only buy the sail? If you just have the sail I'd suspect it may not fit on normal masts at all

If you have the correct mast- sticking the last 1-2ft in is hard. You are sticking a straight pole into a curved sleeve so it takes a good hard push for the last bit. Look for any wave sail rigging video.