Sometimes Office fails to install. Usually will state “Getting things ready” indefinitely:
Microsoft came out with a tool, SARA (Microsoft Support and Recovery Assistant). https://diagnostics.office.com
Download and run the tool. Proceed through the prompts as necessary. This will resolve any issues with the install, or at minimal, give you an explanation on why the install is not working.
In this case, Microsoft Office 2010 64-bit was installed and needs to be removed to proceed with the O365 install.