I might be wrong but I think it's just a guy on pixiv that was doing gifs of some artists. His name was 营养社-EIYOUSHA but the page is deleted now and I can't find his other socials if he even has any.
I am 90% sure that's a file sharing site that no longer exists so the only thing to do is ask for a reupload.
You can still find these in the op
In the 'Feb to Dec 2021' file:
-Summer Barbara (2021-08)
-Summer Jean (2021-08)
-Sara (2021-09)
-Kokomi (2021-12)
In the 'Jan to Nov 2022' file:
-Marin (2022-03)
Use the pixeldrain links so download individual files if you want to skip all the images