After you have purchased the plugin you will get an email from SendOwl with a download link and license key.
After download is complete upload the plugin and activate the standard WordPress way. This is all that is required to start using the plugin.
After activation a notification will be displayed asking you about installing and activating Goose Studio Settings.
Go to Goose Studio Settings Installation Guide to see how you install and configure automatic updates and more. After activating Goose Studio Settings you can reach the Settings page on the plugin page.