EDD Download Pages is fully integrated with EDD Frontend Submissions. With this integration you can let your vendors associate download pages to their existing downloads.
The intention of this integration is bring all the features that already offers EDD Download Pages to an individual website to your multi-vendor marketplace.
For it the Frontend submissions integration provides you a new submission form specific for the download pages post type, new fields to add the desired restrictions and download page hierarchy (post_parent and menu_order) and configurable vendor permissions.
If you have an active install of EDD Frontend Submissions, first you need to go to EDD Download Pages settings page to configure how the integration will work.