I advise all my customers on the following adage:
Deploying an MDM makes everything easier. Deploying an MDM is hard.
Device management is a complex web of intricacies that takes years to master. And at the pace Apple changes, updates, introduces new features, etc., it is a never-ending battle of trying to stay one step ahead of chaos. Add into this the diversity of MDM offerings, and it can be a huge challenge to take the first step. My advice is to always pick an MDM that will grow with your needs. I've learned a valuable lesson years ago. As much as you think you know what you need today, tomorrow those needs will change. Selecting an MDM that has more capabilities than you need today simply means tomorrow you will not be wondering why books don't deliver. Or how to deploy non-App Store apps. Or instead of using a profile template to manage a setting you are now learning how to create custom profiles.
I would suggest you reach out directly to Apple for support on Essentials. Like Profile Manager before it, ABE is inferior to nearly every other MDM. At least Profile Manager could be called a reference implementation. ABE is a... well I don't really have any kind words. Disservice comes to mind. ABE makes the assumption that the devices managed under it will spend 100% of their time within the Apple ecosystem (managed Apple IDs and every app available in the App Store). For 90% of deployments, this is broken the minute you want to deploy and manage Google Chrome. Or Zoom. Or Teams. Or anything from Adobe.
Sorry to hear your struggles. It may help you to reach out for professional assistance. There are many consultants in the Apple Consultants Network that can assist you with the initial setup of your MDM. If you are working with an Apple Store, ask your Business Associate if they have any recommendations.
Hope this is helpful