That’s very outdated, build 756 is from February 2021. How did that happen? I guess it might be too old to do an online update successfully. I would download the installer and reinstall it. Your database should be retained and updated. Nevertheless, before you do anything ensure that you have a current backup of your database.
Are you intending to stay on Roon 1.8 (the Legacy version, which can work in a limited way without Internet) or the current Roon 2.0?
If you want to stay on 1.8 Legacy, see the Download Links for Roon Core 1.8 (Legacy) on this page:
You want the download for MacOS All-in-one / MacOS Remote. Then run the installer as usual.
You will also have to install the Roon Remote 1.8 Legacy from your App Store / Play Store if you want to use mobile devices as remote control.
If you want to update to the current 2.0 (which requires internet access to work), go to this page and click the Download for macOS button: https://roonlabs.com/downloads
Run the installer as usual.
In this case, install/update the regular Roon Remote app from the App Store / Play Store on mobile devices.