Hello You should have received a product key with the trial. It would have been on the download page as well in a confirmation email. If you received that email, you can use that PK to activate the trial. If you had another Office 2011 trial, then you will not be able to use it - as you are only allowed 1 trial per computer. If that does not help, try calling Microsoft and see if they can get the trial up and running: Office Installation and Activation Support (800) 936-5700 Thanks.
13 01 25 Thank you for getting back to me. Yes, I had installed a previous version of the trial before rebuilding my Mac to its default value for personal 'learning purposes'. Talking to Office support, the first time you download the trial, the electronic signature of your Mac is registered on their server. It seems it is the reason why you can't reinstall without an activation key. I even tried to clean the Mac with the following Microsoft KB:.
Again, thank you.
Office Insiders. (Note: The link may say Office 2016, however Office will install the most up-to-date version of the Office apps as set by your Office 365 admin.) This begins the download of Office. Follow the prompts on your screen to complete the install.