It’s pretty straightforward.
This post is talking about using NextCloud app to sync with your own NextCloud instace, but the same steps work when using /e/'s Cloud (which is also a NextCloud instance)
(You don’t need DAVx5 if your happy to continue using /e’s Contacts and Calendar sync, just the NextCloud sync client app)
When the app asks you for the name of your server, use the https://murena.io and use your own full username (xxxx@ecloud.global or xxx@murena.io - whichever your signed up with originally)
To turn off /e/'s file, media and music sync you will need to go into Settings | Accounts, and select your murena.io acccount. Nt sure of the exact sreps after that, but it’s quite simple