This is when you visit Clonfira for the first time with Aidan.
The wording is wrong. You don't need just one placement to unlock this achievement. But one placement in each of the consoles.
When you're back in control, head up the steps to the right, pick up Arthur's cap and the Orb. Now comes the part where you need to be quick.
1: There are 2 consoles on the left. Head over there, and use the Orb with the left console.
2: Quickly take it back out, and then use the Orb with the right console. If you're quick enough, the door will open for you, allowing you to progress and unlock your achievement.
According o creptor5291 and I AM CULLY, you can dashboard, reload and try again should you mess it up first time around. Thanks for the confirmation.