The text provides four methods for subscribing to Pull Requests (PRs) on GitHub, depending on user preferences. These include setting up email notifications by adjusting settings at https://github.com/settings/notifications and customizing further using the GitHub documentation; enabling mobile notifications through downloading and signing in to the GitHub app from https://github.com/mobile and adjusting settings at https://github.com/settings/notifications; subscribing via Slack by installing the official Slack GitHub integration or using Axolo for bidirectional integration that opens a dedicated channel per PR, invites relevant team members, and uses emojis to indicate PR status; and finally, an unspecified fifth method mentioned in a separate article.