I booked a package through Costco and was reading through my final documents this morning.
It says this:
I’ve already linked my tickets on MDE. Do I still have to do this?
If you already have your tickets linked on MDE, you don't actually need the physical tickets then (I'm assuming that Costco sent you electronic tickets). Yo may still want to pick them up when you get there as a backup, just in case? But it certainly isn't necessary.