Not isolated to Windows 11.  I am on Windows 10 with the same issue on 2 brand new XPS machines.  This is ridiculous.  Microsoft is the issue! Update-Resolved-issue resolved after trying multiple times. no further action needed
Just bought an Inspiron 3000 laptop with MS home and office 2021 "preinstalled".  I already had a MS account and used the same email for the purchase.  It never activated.  Spent 4 hours with 2 different techs who only seemed capable of reinstalling office multiple times, downloading office again, checking my dell digital locker (empty), my MS account (again no record). The last tech even contacted MS help and argued with them before ending my session abruptly.  Add I need is a activation key which they are incapable of providing (or finding).  They said it was in the box (no), in an email (no). They don't even know it's a digital key and that it's supposed to auto install when I log into MS!  Now I have an email from Dell saying they can't help me, yet they won't refund the $99 I paid, they keep sending me back to a tech.  You'd think they would cut their losses as they already spent more than that making sure I'll never buy another Dell product again. So session #3 with a "senior" tech didn't occur as they called 1/2 hour early so I couldn't get to the phone, and they didn't leave a direct # to call so I had to go thru the entire menu system again!  Now I'm waiting yet again.  This goes beyond the absurd.  And it seems like I'm not the only one who still has this unresolved issue recently if you search other topics.
Dell techs unable to activate Office 2021 and wont refund