Ensure you are properly logged into your Microsoft account. If you don’t have an account, you’ll need to make one, as it’s required to install Office.
Occassionally, especially for user groups at work or school, permissions issues can cause the installation options to be hidden or moved.
First, try navigating directly to the install link at https://aka.ms/office-install
If that doesn’t work, the most likely explanation is that your admin hasn’t assigned a license to your account. In this case, contact your tech support or authority (such as a boss or teacher) to double check whether permissions and licenses are correctly assigned.