Spoke with customer service and they confirmed that it is indeed per line with the magenta max plan. So each line on the account gets their own 40gb of hotspot data.
Already have an account? Login
Enter your E-mail address. We'll send you an e-mail with instructions to reset your password.
Sorry, we're still checking this file's contents to make sure it's safe to download. Please try again in a few minutes.
Sorry, our virus scanner detected that this file isn't safe to download.