After installing Office 365 on my home computer I got this error message "Sorry, we can't connect to your account. Please try again later". Trying later did not help much, no matter how many times I tried. And all the Office applications reminded me that they needed to be activated. Googling this error message revealed that a many people had this problem, but I could not find a definitive solution, not even from Microsoft. Some of the discussions I found suggested that this was a firewall problem. This is the procedure that finally solved my activation problem:

1. Remove the existing Office 365 installation from the computer using the Fix It tool from Microsoft.
2. Connect the computer directly to your ISP's router using a network cable (not a wireless connection).
3. Start Internet Explorer in private mode, right-click on the application icon and select Start InPrivate Browsing.
4. Log on to your Office 365 account, click the cogwheel next to your name in the upper right corner and choose Office 365 settings.
5. Click on software in the left page menu and choose the Office version you want to install.