If this is for an HTML5 game, then you are probably running into one of two common problems:
- File names are case sensitive on our servers. You must reference your game's assets using the same capitalization
- Only use relative paths to reference resources in your zip. Since itch.io loads your game from a directory on our server, if you use an absolute path your game will look in the wrong place
We have information about the ZIP file requirements on our documentation: https://itch.io/docs/creators/html5#zip-file-requirements
Hope that helps. Tell me if you still aren't able to get it working.