How do I get a Outlook version compatible for my iMac with macOS 12.7?

Graeme Gurney wrote:

My imac is a late 2015 model and I cannot upgrade beyond Monterey 12.7.4. Yesterday my Outlook ceased to open and when I tried to reload it, a message stated that I need a version 13 or higher. Can I use Outlook that does not require version 13 or higher?

maybe the web version

Microsoft only supports new installations of Office on the current release of macOS and the two previous versions. That is the reason you could not reinstall Office or Outlook into macOS Monterey.

The first paragraph should not be the cause for an existing, compatible, and working Outlook installation on Monterey to stop working. That would lead me to believe something happened on the Mail server side, and could be a change in Mail server availability or configuration.

1 - what version of Office are you using? Office for Mac xxxx? Office 365? And what version #?

2 - did you try logging into a different user account on your Mac to see if Outlook works there? It's possible it may have only been corrupted in one user account.

3 - did you attempt to reinstall Outlook? If so, how?

No, unfortunately. Replace your Mac - it’s obsolete (as you’re finding out). Things will only get worse.

As you know Outlook is a Microsoft product, your best bet is asking on an Office for Mac forum or an Office forum.