AutoNumeric is required as ES6 module and not as the distribution version.
When compiling a project using webpack, node_modules is usually not transpiled with babel-loader, resulting in AutoNumeric not being transpiled.

Instead of the ES6 module:

require('autonumeric')

Use the distribution version:

require('autonumeric/dist/autonumeric.min')

It also results in faster compiling and smaller file-size.