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
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Nintendo Switch Online + Expansion Pack Costs $49.99 Per Year
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Nintendo Switch Online's N64 and Sega Genesis 'expansion pack' launches October 25th for $49.99 per year - The Verge
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N64 and Sega Genesis games come to Switch Online, but will likely cost more - Polygon
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