Tell us what you are trying to do?
when user becomes a member and uploads a file for other members to download, i need this file only accessible to download if they are a member themselves currently if a member shares the URL then anyone with it can gain that file.
Is there any documentation that you are following? no just guessing....lol
However based on your explanation it seems that you need a plugin that can manage your media library. A plugin like the one below should be able to help you . https://wordpress.org/plugins/prevent-direct-access/
This should allow you to prevent guests from having access to the files that are stored on your site.