> More importantly, you don't need to get IT or Procurement involved to try slack.
Are you implying you do have to do so to try out Matrix? You can simply use the web version of Riot hosted here (https://riot.im/app) and sign up for a free account on matrix.org.
There's a link to this accessible from the "Try Matrix Now" page you referenced above. Admittedly, it seems the words inviting you to try Riot "on the web" were linked to https://matrix.org/docs/projects/client/riot instead of to https://riot.im/app/. That's probably a mistake and should be fixed.
You can create your own rooms (which are like IRC channels) which can be invite-only.
The counterpart to Slack workspaces/"servers" would be Matrix communities. They allow you to group a bunch of rooms and users together for discoverability. The feature exists today and is usable but still not as polished as one would hope for, but I think work on this is coming up soon.
In particular, I think better community front pages (describing the community, supplying related URLs and such) and access control (such the ability to restrict joins to community rooms to community members without having to invite each user to the room separately) are things that will be worked on.
Are you implying you do have to do so to try out Matrix? You can simply use the web version of Riot hosted here (https://riot.im/app) and sign up for a free account on matrix.org.
There's a link to this accessible from the "Try Matrix Now" page you referenced above. Admittedly, it seems the words inviting you to try Riot "on the web" were linked to https://matrix.org/docs/projects/client/riot instead of to https://riot.im/app/. That's probably a mistake and should be fixed.