I have previously provided an in-depth explanation about NextCloud with Collabora Office Online and how we've installed it on Ubuntu 16.04. This is an update both of the process, and of the technology.
Update 2021-11-08: this post is now getting a bit long-in-the-tooth, and I need to update it to use up-to-date components. It might still be useful to folks, but use it with caution. Also, please note, we're using NextCloud with OnlyOffice (the open source community edition) these days.
One of the OERu's most compelling technological capabilities is the set of internally developed open source tools that allow us to automatically transform and inject a collection of MediaWiki content on WikiEducator (usually in form of micro-courses) making up a course into a mobile-friendly, easy-to-navigate WordPress site, usually situated on OERu's Course WordPress Multisite implementation.