You must have admin access to share your app with this method.
Using a link lets you use your custom app only in those organizations you want. You need to manually add the app to each organization.
Go to My apps and click on the app you want to share.
Click Publish.
Click Share a public link.
Open the link and click Install in the new window tab.
Select the organizations you want the app to be visible on and click Install.
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