No people tab in photos

Did you try it this way? How to share albums in Photos on your iPhone, iPad, and Mac

Create a new Shared Album

1. 1. In the sidebar, click the Add button  next to Shared Albums.
   2. Type the email addresses of people you want to share the album with. Click the Add button  to select contacts from iCloud.
   3. Click Create.

You do not need the Peoples tab to create an album and to invite People to it, only when you want to manage an existing shared album. Clicking the Add button ⊕ next to Shared Albums will open a panel, where you can add subscribers. Click the ⊕ button in the second field of the panel to add a Contact from your Contacts as a a subscriber to be invited.