The quick version
The process for installation over an existing Excerpts+ is to deactivate existing one, install and activate the new Excerpts+ using the WordPress plugin installer, and then work through all existing Excerpts+ blocks ensuring all their settings are correct, paying particular attention to Image Widths, and the Structure. You will also need to re-publish any page with Excerpts+ blocks on it., even if you don’t make any other changes.
In your WordPress, under the Plugins section, find and deactivate your existing Excerpts+ block plugin. If you do not deactivate the old one first, you will get a fatal error message.
Still in the Plugins section, select the ‘Add New’ plugin option and upload the Excerpts+ ZIP file.
Activate it when prompted.
That’s it! You can now move on to chapter 3, on Using Excerpts+.