I couldn't get the script here to work, so decided to write a new one.
I followed this very useful tutorial here to get started https://macmost.com/export-all-of-the-notes-on-your-mac-using-a-script.html
The difference is, my script will let you choose which folder in Notes that you want to export (you can multi select) then it will create it as a Notebook in Evernote.
This works on macOS Catalina 10.15.6.
Follow the steps in the link above but use this code instead. Enjoy
// set things up
var app = Application.currentApplication();