In the depths of Hell.

Thank you for the quick response. I apologize for the inconvenience; I didn't notice that there was another portal leading to two different locations. So, it turned out that I missed the very first Castle and the building within it. They showed a video with the altar, and the passage opened. I'm trying to read the forum carefully, but there wasn't an answer to a similar question, so I assumed there might be a bug or some kind of incompatibility. Thanks again, I'll continue playing.