Let's walk through creating a standard Build VM
Step 7 - Describe your Configuration
Initial documentation on this topic can be found here. First, look at this article which goes over how to configure your ConfigTemplate.xml file for your environment. Next, look at this article which covers how to configure your DatabaseTopologyDocument.xml file as well as your NodeTopologyDefinition.xml file. The minimum number of nodes you have have in a cluster for Dynamics 365 For Financial and Operations, without changing some standard configuration files is 5. You can get away with 4 if you make a few changes a few configuration files as outlined here.