Hello there, jrlomr. While waiting for your answer to 4Gal's follow-up questions, I am also joining this thread to provide information about accessing your company file successfully.

QuickBooks versions from 2015 to 2018 are no longer supported. The reason your computer crashed when opening your company file is that you are using an unsupported version of QuickBooks that doesn't meet the system requirements.

To prevent any loss of your company file, you can utilize our QuickBooks Desktop Mac trial to restore your company file to the latest version. From there, create a backup copy of your company file so you'll always have a copy of your financial information. It helps you restore your file whenever needed.
 

Once you have made the decision to upgrade your company file and access it using your new Mac mini device, you can proceed with the installation and setup process. Install and upgrade your company file by following the steps outlined in this article: Install and set up QuickBooks Desktop for Mac.

However, if you want to keep the current version you have, I recommend continuing the download/installation process on your old Mac if you are still using it for compatibility.  

I also recommend checking out this article on the new features that have been added to QuickBooks Mac Plus 2023: What's new in QuickBooks Mac Plus 2023.

If you still need more information and further help accessing QuickBooks successfully on your device, please don't hesitate to add another post. I'm here whenever you need assistance. Take care and have a good one.