We offer a non-profit license for open-source projects [0] with special nonprofit pricing. We also plan to move the System Permissions Scheme into the open source Team Edition with the 6.0 release on September 15 [1].

Thanks for being a user, feedback is always welcome!

[0] https://mattermost.com/nonprofit/ [1] https://forum.mattermost.org/t/granular-permissions-coming-s...