No SMS provider to set up. There is no Twilio account, no phone number to buy, and nothing to configure. Type in the mobile number that should get notified and turn it on.
SMS credits are billed separately from your plan, since a text costs money to send regardless of how many integrations you run. You only pay for the texts you actually send.
Keep the message short. SMS is billed and split in fixed-length segments, so a longer message can quietly become two or three texts instead of one. Include only the fields you actually act on, usually the name and phone number, rather than every answer on the form.