Games that are free and has custom price for file, they don’t see the files in bundle page for the bundle purchased.

Based on a quick look of your pages, you are using Individually Priced Files to set the product price of your page. We strongly advise against that since it can have side effects on how ownership works.

Please read our guide here: https://itch.io/docs/creators/pricing#purchase-tiers-through-individually-priced-files

Individually priced files come with an important distinction regarding ownership: The buyer will only continue to have access to these files if the price they paid satisfies the minimum price you set on the file. This means that if you change the individually priced file to be more expensive, you may lock out access to that purchase tier from existing buyers. We strongly recommend considering how you intend to price your project in the future before using an individually priced file. Use individually priced files for quick bonus content, not to set the price of your content. Use the minimum price on your project to set the price of your product, as this will allow you to change the price at a later time without affecting ownership.