Exactly.

I did a deep dive into the Cyclorama content and found that it did not come as part of the Poser Legacy package; there was other content that did something similar.  That was my bad.  I do not know where the Cyclorama background files are installed on DS.  As I stated, Cyclorama is very old content that no one uses anymore.  I still have a copy of it for Poser and I did look at it.  It is nice but not practical when you can use HDRIs for background images and lighting.  In addition, the formats for the background images will cause visual distortions if you simply try to import them directly into your program.  And lighting will be close to impossible to match for a decent render.