This is exactly correctIf I underastand things properly, we have two options for proceeding, that I've noted on the image below:
1. the arrow. I think that is the doorway that is being operated by the key.
2. the circle (ok -- "circle"). There is a lever and apparently two doors. That's my proposal for which way to go next, but I think someone should just pick a route and we'll follow.
Onwards!
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