Getting undefined calling auth.getAccessToken()

[windmemory]

My code is exactly the same as the example

import Authenticator from 'openai-token'

const auth = new Authenticator('valid-email', 'valid-password')
await auth.begin()
const token = await auth.getAccessToken()
console.log(token)

There is no any error thrown in the console, I just got undefined in the output. Is there anything I need to add here to make it work?