Currently, the only way to add packages/assets is to manually download them. For now, there is not much packages/assets so it's still good. But for the future, it would be a big problem, when servers owners want to add a lot of them (such as maps which can exceed GBs)
So, to fix that I suggest to add a unique identifier for each packages/assets on the Vault. They will be displayed on the right side of each packages/assets page, where all the information is. (See screenshot below)
Then servers owners have to put them in Config.toml packages/assets fields and the server will fetch them and download them.
For security and reliability purposes, I think it would be good to require the Server authentification token to enable this feature.