Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Sorry, if a particular document is password-protected, there is no way to circumvent that password.
On the other hand, if you are saying that you need to activate your Office installation, you usually do that by signing in to your associated Microsoft account. For more, see https://support.microsoft.com/en-us/office/activate-office-for-windows-5bd38f38-db92-448b-a982-ad170b1e187e . If you don't have a Microsoft Office product (perpetual license or subscription), you will have to get one first.