Office 2021 Home & Business one time download not activating when I sign into Office

Had a brand new Vostro 5320 arrive yesterday which I bought a 1 time download for Office 2021 Home & Business for.

Following many different instructions on how to install the software I was told to open Ms Word (pre installed on the laptop) and sign into my Microsoft account. I have now done this however no such product activation has occurred. Microsoft Office asks me to either download a free trial of Microsoft 365 which I don't want, or enter a product key, which I don't have. Every where seems to say the product will just "activate" itself once I sign into MS Office but this just has not happened for me. I contacted Dell support who told me to do the same thing, even though the reason I emailed them was because I'd already tried that and I listed this in the ticket.

I checked the invoice and can clearly see the purchase for Office 2021 Home & Business - I originally thought I'd just forgotten to add it to my basket and therefore hadn't actually paid for the product but this isn't the case.

Can anyone advise what steps I need to take to get the product key for the software that I purchased? Or who I can contact that can give me the correct steps to get the product installed or the details of a team that can remote into my laptop and install the software for me?! 

Thanks in advance for any help/suggestions!