Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
The 'Service Unavailable' usually indicates there is a problem with the Office licence.
What version of Office 2024 did you purchase, is that Office Home or is it a version like LTSC, Standard or Professional Plus?
If the licence you purchased is Office 2024 LTSC, Standard or Pro plus, then that is a volume licence version of Office used by large organizations, it is not a correct consumer Office licence and you will not be able to use that licence, you will need to contact the retailer to get a refund for your purchase, they should not be selling that type of Office licence to the general public.