Generally, you don’t want to use POP any more.
POP downloads the files to your computer and won’t sync with any other device, like a phone or tablet.
That means when you delete the message on the computer, you will have to delete the same message on the phone, and delete the same message on the tablet.
IMAP is a better option if you have multiple devices.
Everything is synced through the server.
For Road Runner, you can use mail.twc.com and the IMAP and SMTP server. That also means you can send mail when you are not connected to the RR service.
I usually setup one device as POP and IMAP for the rest so the POP device will have a permanent copy of all my messages but the other devices will still be able to access mail going back a few months. You can keep a local copy of all messages using IMAP but some mail clients make this easier than others.