It’s an old version, so a potential bug was perhaps fixed. We don’t run such a version to reproduce, and even if there was a bug in that version, it wouldn’t be fixed.
So the normal way is that you upgrade to a current version, you check if the problem is still present, and then we proceed.
I have neither understood the problem nor do I see an outdated version of anything here.
What is your Nextcloud version? Open https://cloud.server.tld/status.php (your Nextcloud address with /status.php)
Can your wife log in web-based at https://cloud.server.tld (your Nextcloud address)? Does she see the shared link there, e.g. in the notification, regardless of an email? How does she want to access it? With the browser or a Nextcloud app.
The screenshot with the users doesn’t seem helpful to me. You can also upload screenshots directly in the forum here. You do not need Dropbox for sharing screenshots.
You have posted your name and email with the Nextcloud. If you post the url of your Nextcloud we can check the Nextcloud version for you.
Clarify how updates are carried out for you. It could be, for example, that your PHP version is outdated and therefore you have not been offered any updates. However, I do not know whether you will still be offered updates when you update your PHP version.
You should probably have taken care of this beforehand.
In case someone from Nextcloud GmbH or Nextcloud devs are reading along:
Maybe you could enter the release period in the management GUI of Nextcloud (/settings/admin/overview). Then Nextcloud administrators might realise earlier that the release is outdated or will be outdated.
Ok. then we ignore the fact that the Nextcloud version is outdated. Please describe in more detail what the actual problem is. You write that you want to share a folder with your wife. However, your Dropbox screenshot only shows your two users. Show a screenshot of the attempt to share the folder.