I'm getting my first sugargliders here soon and am trying to get the cage ready. I'm confused, there are so many different opinions. If the glider is not a joey, do they need to have the wire mesh for the cage or are horizontal/vertical bars fine for a cage? I appreciate any advice.

The bars are fine, there is no need for the wire mesh as long as your bar spacing is narrow enough, less than 1/2", so they can't get out.