Ah, sorry. The app won't set things up on its own, I would need to collect all downloadable entries and package them with appropriate metadata, but with well over 200 entries submitted it becomes too unfeasible. ^^'
Viewing post in Using a Jam Player, maybe?
On the repository I linked, there's a separate Jam Packager project, that handles editing and saving all the relevant metadata (also some quality of life features like automatically unzipping all the ZIPs of the downloaded entries). Once you save the metadata, you can open the Jam Player from within the folder which has "jam.jaminfo" file and it'll show the entries correctly.