I don't see any data after signing in
Connect an ad account in Settings → Integrations first, and make sure the account is assigned to the brand you're currently viewing. See Connecting accounts.
My colleague can't see the same workspace
Make sure you're both in the same organization. If you each signed up separately, you created two independent organizations. One of you needs to invite the other from Settings → Members using their email. See Inviting your team.
I can't find the Connect button / can't connect an account
Connecting accounts requires organization Admin permissions. Ask your organization admin to connect it or upgrade your role.
How do I switch organization or brand?
Use Switch organization / Switch brand in the top-left corner.
Where do I start?
Run through the Checklist in the left nav, or follow the Quickstart end to end.