I'm using AutoTag in Word to create my template, but when I try connecting to my JSON data, I keep getting an error:
Exception of type 'System.OutOfMemoryException' was thrown.
The JSON is on our network and isn't accessible to anyone outside the company so I can't share it.
You are almost certainly running the 32-bit version of Windows. This forces AutoTag to 32-bit mode, even if you are running a 64-bit version of Windows. That means you have 2G of memory for Office, AutoTag, and a copy of your JSON file.
If the JSON file is big enough, it eats up all that memory. In this case your options are switch to the 64-bit version of Office (assuming you're on a 64-bit version of Windows) or reduce the size of your JSON file.
(disclaimer - I'm the CEO at Windward)