Multiple factors help determine the amount and type (4G LTE and 5G) of data businesses need for their failover/fixed wireless access solutions. For simplification, you can boil it down to these two factors:
Bandwidth is the maximum amount of data that can be transferred at any given time. Think of bandwidth like a highway with multiple lanes and the technology and tasks your business performs as the traffic that takes up the lanes. To determine your bandwidth/data needs, you need to identify how many lanes your highway needs for your business traffic.
You could take the time to identify how much bandwidth each of your network traffic uses and do the math for an exact answer, but that can be time-consuming and difficult. For a quick idea of how much data your business needs, use the flowchart below (based on general use cases).