CIOs must pay attention to NextCloud.
It is an open source solution that kinda let you run your own Google Drive, own Google Apps, own Dropbox, own iCloud on your own servers and storage.
Has an App Store with hundreds of extensions, vibrant community, supports multiple users with file sharing and pretty advanced collaboration, conference calls, corporate mobile device management, security and encryption, and much more.
They also provide free and mature desktop and mobile apps that let users sync part or whole filesets with their devices for offline use (similar to Dropbox but limitless and with far more features). I’m running it on my family server and my folks (and me) are pretty impressed.
Requirements are just LAMP (Linux, Apache/NGINX, MariaDB and PHP).
In a world increasingly dominated by services on expensive clouds, an open source solution as NextCloud is a refreshing option for the cost-savvy.