This article explains migrating Confluence plugins from one Cloud instance to another.
Introduction
For Copy Page Tree, no additional steps are involved. 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 the plugin is intended for use in the new instance, you will need a license.
Prerequisites
The Copy Page Tree plugin should be installed on the source and target Confluence Cloud instances.
A valid 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.