I don't understand what you mean. My repo contains all my work, but not the asset pack containing the materials and some prefabs. This is as instructed, Also there is a readme with the asset pack listed.
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When you build your game, in the Unity build settings you select a folder to save your build to. Everything in that folder needs to be uploaded to itch.io for others to be able to play your game. Try downloading some of the other submissions, unzip and look at the files included and you will understand.