Installation?

I don’t understand the installation process. It says to do this:
“Place one of the template tags in a WordPress template. When that template is used, an extra editor will appear in the back-end.”

I don’t understand how this would have any effect on the admin pages. I must be misunderstanding the instructions.

I want to use this plugin for a custom post type “project”, and possibly on two static pages later on. Is the editor actually aware of the template file that will be used? If I configure my theme’s index.php, page-about.php, page-home.php.. all of them differently, what is going to happen? How would it possibly know what content blocks are available to which pages?

https://ww.wp.xz.cn/plugins/multiple-content-blocks/