Had https://assetstore.unity.com/packages/essentials/game-jam-menu-template-40465 been an asset that had been provided for this jam? I just came across an entry that says it made use of it but it seems I would have had to catch it in time and now I can't get it anymore. The game's linked source-repo on github only contains the contributed bits, so without that asset as a template one can't do anything with it...

(I do have that Game Jam Starter Kit that I downloaded separately, though. So if the linked asset from the store is contained in that archive it could be possible to make it work...