Installing the plugin
After purchasing the plugin, you should receive a purchase receipt via email. This email will contain a link to download a .zip file of the plugin. Save the .zip file onto your computer, then login to WordPress.
Then, navigate to Plugins » Add New and click Upload. Click "Choose a File" to open the file browser and select the book-database.zip file, then press "Install Now". Once installed, activate it, and then you’re all set!