If you wanted them to appear as a ‘fake’ album of your own creation then just putting them in a folder is not enough. Otherwise, Roon will treat each track as an album entry that only has 1 track available.
You need to edit the tracks metadata and:
- Make sure the album artist is “Various Artists” for all tracks
- Make sure the album name is the one you are using for your compilation
- Make sure they are all Disk 1
- Make sure that they are all different/sequential track numbers.
See; How to create an album with 500 songs - #5 by StereJo
Or, see, next post for alternate suggestion