Create CloudPages to collect and subscribe users is the correct answer. CloudPages is a feature that allows you to create web pages and landing pages using Marketing Cloud tools and data. You can use CloudPages to collect information from users who visit your pages from social channels, such as Facebook or Twitter, and subscribe them to your email lists or data extensions. You can also use CloudPages to create preference centers, profile centers, or unsubscribe pages for your email subscribers. You can learn more about this in the
[CloudPages Basics] module on Trailhead.