SOLVED problem with Windows Mail app and AOL email access:
Here are the steps I took to allow me to access AOL emails via WIndows Mail after AOL required new authentication in 2020.
Essentially, you will let AOL generate a password for you to enter into your Windows Mail app. It was a set of 16 letters, such as this example: XUHO PSIY BBWF ZLKM. This is not the same password you'll use to login to AOL, but a special password to authenticate your third party email reader (Windows Mail in this case) with AOL.
From my memory, the basics are thus:
1. Go to www.aol.com and login
2. Go to AOL Account Security and follow instructions for gaining access to you AOL security settings.
Look for an item allowing access to third party email apps.
3. Select that Mail app that you use from a drop down menu. Note: Windows Mail will be "OTHER"
4. AOL will generate a password for you to enter into Window Mail account settings. Copy the AOL now generated password, then navigate to your Windows Mail app AOL account settings, and paste the AOL-generated password into your email app password field.
Your AOL emails should now populate within the Windows Mail app.