If your Office 365 applications do not open after the installation, or you get an activation error, a license error, or the "Your account does not allow editing on a Mac" error try running the Licence Removal Tool on this Microsoft page. After running this tool re-start your machine and sign-in to word or excel etc.
If the above steps did not work, try the following:
1. Make sure that your Mac has done all the available updates for the OS. It is also good to back up everything just in case something unexpected happens. You can use Time Machine to help you with this.
3. If there are still issues uninstall office. Follow all of the steps in this article.
If you have other licence or activation Office errors visit this page to follow steps to resolve specific errors. If you can't activate Office after installation, follow the steps for "can't activate office after installation" on the above page.