Get a Plugin ID
Each Marketplace listing should have a unique Plugin ID. The plugin package manifest should use the same ID that is associated with the listing. You can obtain a unique plugin ID in any of the following three ways:
Build your plugin using UDT, and once you are ready to publish click on ‘Share on marketplace’. From the Developer Distribution home page, create a new listing and simply copy the unique plugin ID generated. Replace the ID in your plugin package manifest with the copied plugin ID.
Create a new listing from the Developer Distribution home page and download a starter package from the "Listing Overview" page, which will automatically contain the new plugin ID.
Add a plugin to a project in Developer Console and download a starter package. Click on "Distribute" and you will be redirected to the Developer Distribution "Listing Overview" page.