Firstly, I suggest installing the NextCloud app from F-Droid rather than from /e/'s Apps store: you will see more information, and will receive app updates more promptly.
The app you need is the NextCloud synchronization client: I think that is the first one in your list, but it’s hard to tell from the limited information is that screenshot. In this screenshot (taken from F-Droid app), it is the sixth item in the list, showing version number 3.17.0, which is the most recent stable release.
You don’t want ‘Nextcloud Dev’: that is experimental, and only for people who want early visibility of new features (even if they don’t work fully), and are prepared to put up with possible ‘breaking’ changes