Fail to extract data from the dynamic source

I added a metafield named “files” which accepts all types of files and is used in the collapsible row on the product page. However, I cannot find it from the dynamic source. Instead, I can only find other metafields that belong to “text” or “multi-line text”. Could anyone help me fix it? Thank you!

Not all input types are accepted within Dynamic Sources.

Please refer to this documentation for more information.