You need to go to the tap-stiles all the way on the left as you approach MK. There will be someone there checking for PPO ADRs. They will scan the band of the lead on the reservation to verify the reservation. You will be given a piece of paper.
You will then break off to the left at the hub - look for the person holding the ADR sign. Then when you get down that path a little bit, your piece of paper will be taken by a group of CMs (your group needs to stay together), then it's over the bridge (there was a photopass photographer there on the bridge, good and different perspective of the castle in the background).
We had an 8:20 ADR at BOG, we were able to check-in at 8:00.