Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
First, I really don't know what "Microsoft Office Windows XP Home Edition update" is. I have to assume you have an edition of Office XP, and possibly a version upgrade license.
If you have the installation disc for Office XP, insert the disc and let autorun start it up. Does it tell you that it can't find a qualifying previous installation of Office to upgrade?