NOTE: Since this is a question, not a blog post, please use Discussions to post something like this next time.
The Persons app is a profile module. UNA separates Accounts from Profiles, so your users can create public profiles of different types and on implementation stage you can decide what kind of profiles to support. For example, one user may choose to have a personal profile and a company profile when using your site.
If you want a more conventional, streamlined experience, you can set "Default Profile" in UNA Studio (Studio > Settings > Account > Default Profile Type). This will redirect newly registered users to the form that creates a public profile of your choice right after the initial registration. In effect, it would work/look like a two-step registration form.