Purple And Blue

I'm on the quest "Purple and Blue" and I'm at the part where i'm at the underwater village. I killed the chief of that village and got the eye of ender looking thing, but idk where to drop it. I watched a guide video on it, but when I dropped it at the altar it didn't open. Where do i drop it?

 

I believe dropping the eye of ender no longer works. Instead, you have to right click the enchanting table inside a building near the villager with the eye of ender in your hand. (A door will open after you do this, it should be in the back of the cave.)

If that doesn't work, I'm not sure what to do.