Fix Microsoft Office 0xD000FFFE activation error on Mac

1. Close all Microsoft Office apps
2. Run following:

# Stop Office 365 Service
killall Office365ServiceV2

cd ~/Library/Group\ Containers/UBF8T346G9.Office

# remove all files that start with 'c' or 'e'
ls -a | perl -n -e 'print if m/^[e|c]\w/' | xargs rm

From https://answers.microsoft.com/en-us/msoffice/forum/all/error-code-0xd000fffe/3e8625a2-28ca-4356-b0dc-f57b7a2a58b9