That directly tells you it's talking about ACL for extensions. We don't have a specific integration with Remository. You control access to downloads/files in most if not all download/file management extensions using ACL and CBSubs can give them a usergroup based off subscription to then give them access to those downloads (see "User Group" parameter under the "Access" tab of your plans).

We are not and have never been the developers of Remository nor have we provided a specific integration for it as again that sentence clearly states ACL.

You'll need to find a download/file management extension on the JED that's compatible with Joomla 4. I've already provided you links for this and examples of how you can use 2 of our products for this. CBSubs can then control access to those downloads using ACL or worse case protect the URLs to those extensions using By URL Part protection.

I cannot suggest anything further until you pick a download/file management extension to use for your files.

Maybe our CB Package Builder add-on, that we are using ourselves too for our Downloads section (that we developped in replacement of another non-existing-anymore downloads manager too) could do the task for you too ?

www.joomlapolis.com/addons/cb-package-builder