I am trying to design four panel booth design W: 0.5 x 5.5 x 2.5 x 0.5m and H: 2.5m. What would be the best way to start and save the files. 5.5m is too big for InDesign.
I recommend not using InDesign for panel graphics. It's mainly for document design. For large format graphics I reccomend using Illustrator.
I believe the largest artboard size in Illustrator is 220 inches, but you achieve 5.5 meters by designing in fractions.
25% of 5.5 meters is 137.5 centimeters, so make an artboard that size or at the fraction you want. When exporting your art you can blow it up 400% or this can happen at the printers end.
A word of caution: vector art will scale up nicely but if you have photographic content you should make sure it looks sharp at 5.5 meters big.