If you want to set up a roadrunner email on iPhone or then you need to follow these steps:
Go to settings then go to the mail option

Go to accounts and click on add account

After clicking add account click add mail account

Type your email address and password and click next then click saves.

That’s how you can set up your roadrunner email on an iPhone, if you need to set up a roadrunner email on a mac go to the mail option and follow the above steps.