filipesaraiva at this time the document servers for OnlyOffice or Collabora won't run on our platform because the server operating system is too old.
We hope to have new servers with a newer OS in the future but for now if you want to use those features you'll need to configure them to use an external document server.
If you want to do simple collaborative document editing, you can install an Etherpad app via your Opalstack dashboard and then enable Etherpad in your Nextcloud apps. This will let you create and edit new pad files in the Nextcloud file manager, and you can export those files to various formats as needed.
In either case I do think the Value Stack plan should be sufficient as long as you don't have too many other apps running. If you find that you need to upgrade then feel free to reach out to our support team for assistance 🙂