Copilot Chat is the Copilot most people already have without realising it. It comes with an eligible Microsoft 365 work account, so there is nothing to buy or switch on yourself. You find it in Teams or at copilot.cloud.microsoft, and it answers from current web results with citations. Enterprise data protection means your prompts and company data are not used to train the models.
What it does not do is read your mailbox, calendar and files the way the paid Microsoft 365 Copilot add-on does. Use it as you would Claude's own chat: everyday questions, drafting and quick research. If Copilot shows up in Teams or the browser but not as a pane inside Word or Outlook, this is the tier you are on.