Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
I'm afraid that phone support from Microsoft is very limited these days. You can try the chat via https://support.microsoft.com/contactus .
You have posted to Q&A which is a user-to-user forum. You are welcome to ask your peers in the forum for assistance, and someone may be able to help. You are likely to get assistance more quickly compared to chat support.
I take it you are trying to install Office on a new PC? In most cases, you can just install from your associated account at https://account.microsoft.com/services .
Some perpetual (one-time payment) licenses may require further steps for activation, though; see https://support.microsoft.com/en-us/windows/activation/activate-microsoft-perpetual-products-using-the-product-activation-portal .