Nintendo Switch Online members at over 32 million, service will be improved and expanded
Nintendo Switch Online: How to sign up for the paid multiplayer service - CNET
You need a paid membership to Nintendo Switch Online to play course world in Super Mario Maker 2. Pretty sure you could access course world at no extra cost in the original
How to Set Up a Nintendo Switch Online Family Membership - Nintendo Switch Guide - IGN
Nintendo Switch Online membership: what you need to know | TechRadar