Concurrent editting a page

I am searching for a way to enable concurrent editing of a page / simultaneously editing / collaborative editing in really real-time for Plone 5

I 've found

Is there a free, locally hostable variant of collaborative editing a page in really real-time in Plone 5 ?
Maybe a markdown Editor ....

Google for "collaborative markdown editor" and you will find solutions but nothing that is integrated with Plone.
Only my Smashdocs integration and the integration of Quaive with XXXOffice (for the name) are the only working collaborative editing solutions for Plone (or Plone Intranet).

-aj

Thanks

(CastleCMS (built on top of Plone 5) has etherpad integration. See http://github.com/castlecms/castle.cms)

Do I have to enable it somehow in CastleCMS ?
I managed to install both Etherpad and CastleCMS, I've added Etherpad URL and APIkey, what now? It does not look like, Etherpad is picked up by CastleCMS, there are no pakets to the etherpad port and I do not found any editor preference to activate it or a special content type to add.

This is 'quite off topic', but I noticedI that https://stackedit.io claims to allowing 'Simultaneous collaboration.' (you can install it locally, as well as probably a couchDb.

I never managed to make a 'plone plugin' or to 'get it to work with the (local) CouchDb, but for 'someone who knows what (s)he is doing, it is probably not too difficult.

BUT: reading the GSOC idea: GSoC 2018 Ideas: IFTTT plugin

Could it be done 'that way'. If yes, I assume there are quite a few 'similar use cases'.