Access to community rooms is mostly public. Many rooms are bridged already to corresponding IRC channels.
In case of problem, you may contact User:Strk.
OSGeo does not currently host a Matrix homeserver but might do so in the future, see https://trac.osgeo.org/osgeo/ticket/2309 for updates or help on that task.
To fully use Matrix, you should register your irc nickname with matrix. To do so
- in matrix, open a room connection to
@freenode_NickServ:matrix.org, this will connect you to the freenode nickserv
- enter the command
identify [<nickname>] <password>This will register your matrix user with your irc nickname
- to do this automatically each time, open a direct chat (in matrix) with
!storepass nickname:passwordto store your irc nickname and password with matrix to send automatically when you login to matrix
Then restart your matrix session to test