Miscellaneous topics that do not fit into specific categories.
When you activate an Office licence, the licence should become automatically associated to your Microsoft account online as a digital licence, and it is from your account online that you can re-install Office without the need for a product key.
If this is a first time activation of the Office licence, do you have a product key card?
If so, log into your Microsoft account on this link to register your licence to your account.
https://setup.office.com/Home?wa=wsignin1.0
Then, you should see your Office licence registered on your account on this link.