If you haven't already done so, sign up for an account to store your Gatekeeper configurations. Don't worry, there's no need to purchase credits to try Gatekeeper out.
Gatekeeper works great as a tool to help upsell your users. If your site has a free sample and subscription system, you'll want a page to show users once they've hit the free sample limit. Even if you don't want to upsell users, what page do you want them to see if their visits have exceed their welcome and Gatekeeper returns a "deny" authorization? Alternatively, if your policies might return "captcha", you'll want to create a way of presenting a CAPTCHA and returning the result (solved or failed) back to Gatekeeper.
Page groups are used to organize different types of pages on your site. For example, you may want to distinguish between content pages and landing pages when creating your rule set.
Visitor groups are used to classify visitors based on various details, such as country of origin or IP reputation.
Policies define the rules for your website. You could set up policies to limit the number of free articles a user can view per month, require less reputable visitors to solve CAPTCHAs earlier than regular users, and so on.
You can make sure your configuration is working as expected using the visit tester.
Gatekeeper requires some light technical setup to work on your site. Once complete, anyone with permissions to manage your account can configure rules without needing to touch any code.