Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Try phone activation. See https://support.microsoft.com/en-us/office/-telephone-activation-is-no-longer-supported-for-your-product-error-when-activating-office-9b016cd2-0811-4cb3-b896-5a6a13177713 (even if you don't see the exact same error message as the one mentioned in the article).