Connecting is the one thing on this tab worth walking through, because the first screen asks you to choose between two paths and the choice is hard to undo. Here's which one you want.
1
Getting to the connect screen
Add number in the left rail starts the connection — it reads Change number instead once a number is already linked, but it's the same screen. What opens is a choice between two ways of connecting, and it matters more than it looks: they produce genuinely different setups, and moving between them later means reconnecting from scratch. Whichever you pick, the last step hands you to Meta, so have the Facebook account that administers your Meta Business Manager to hand before you begin.
2
Which of the two to choose
The screen heads this Key detail to check before you connect, and it isn't overstating it. The first option — use a phone number that is not linked to any WhatsApp account — moves that number onto the API, where it lives only here; the WhatsApp Business app on it stops being how you reply. It needs a number that's on no WhatsApp account at all, personal or business, so an existing one has to be de-registered with Meta first. Pick it for a fresh line, or when you want every conversation in one shared inbox. Connect Your WhatsApp Business App with Coexistence is the other shape, and it shares the number instead: the app on your phone carries on exactly as it does now while the same number becomes reachable here too, with your existing contacts brought across and the last six months of chats as well if you allow it. Pick it when the number is already in daily use and giving up the phone app isn't an option. The first option is selected for you — so check it says what you want before pressing Connect.
3
Finishing in Meta
Both paths end the same way. The screen walks you through what's coming one step at a time — signing in to Facebook, confirming your business details, naming your account — and then hands you to a secure Facebook window where the connection is actually authorised. That popup belongs to Meta, so follow what it says rather than anything here. Two things smooth it out. Read the steps on screen before you open the popup, because backtracking inside Meta's flow is harder than getting it right the first time. And if you're taking the coexistence route, keep the phone running the WhatsApp Business app beside you — one of Meta's steps asks you to scan a QR code with it, and that's the one people aren't ready for. If the popup closes before it finishes, nothing has changed and you can start again.