This is O20, the Office365 alternative for Linux.
Note: O20 is no longer actively being developed, but a new (although still in heavy development) version of it called KO20 is now being developed in QtQuick. See https://snapcraft.io/ko20 and https://gitlab.com/abstractsoftware/ko20 for more information.
Snaps are applications packaged with all their dependencies to run on all popular Linux distributions from a single build. They update automatically and roll back gracefully.
Snaps are discoverable and installable from the Snap Store, an app store with an audience of millions.
Enable snapd
On Debian 9 (Stretch) and newer, snap can be installed directly from the command line: