That bike is too small for you even though it is a xl. or you desire a unconventional fit.

a longer seatpost will help with your leg extension but hows your reach??

if you ride with your post above the minimum insertion line you have a very real possibility of destroying your new frame. do not ride it like that.

Im only 5'10 so I dont know what the options are for taller riders but most likely a longer post is not the correct answer.

If you can return the bike and start over you should. You are now more knowledgeable as to how you want your bike to fit and feel.

gluck.