This article explains how to migrate Confluence plugins from one Cloud instance to another.
Introduction
For Copy Page Tree you don't need to take any extra steps. The Copy Page Tree plugin does not store any of your content. It is briefly touched during the copy process, but once that has been completed, the plugin has nothing more to do with it. If you would like to continue using the plugin in the new instance, you will need a license there.
Prerequisites
The Copy Page Tree plugin must be installed on both the source and target Confluence Cloud instances.
You must have a license for the Copy Page Tree plugin on the target instance.
Steps
Export the Confluence spaces from the source instance.
Import the Confluence spaces into the target instance.
Verify that the Copy Page Tree plugin is installed and licensed on the target instance.