First of all, thanks for using our assets; we're glad you raised the question. Also, we really appreciate your efforts in keeping audio files out of your repo and sharing the original site itself. We understand your concern and would be happy to help you.
Yes, the license file does not permit any form of redistribution, which means that adding audio files to an open-source project on GitHub would allow others to fetch those files without getting them from the original source, hence, it's a form of redistribution of the assets. This is the reason why big Game Development companies tend to discontinue their product once the license of assets used are expired and sometimes can't put the project into the public domain as they don't have rights for certain assets used. With that being said, it is not allowed to do so as per our license.
We understand that it's difficult for users to download the entire package to get one of the songs used in your project, but currently, we don't have an option to download individual files from the pack. However, we are working on this update, and it will be rolled out to the public soon.
The credits and the way they have been linked to the original source are acceptable and are within the bounds of our license file. We would love to help you get out of this situation, so, please mail us at - firstname.lastname@example.org . There are a few solutions that could work for both of us, Happy developing!