You can think of the NFT as some "digital certificate of authenticity" of a work that can't be counterfeited. This "certificate" always contains the author, or rather the address of his crypto wallet. The crypto wallet address is displayed in the public profile of the Funrise user and is visible to everyone. By verifying this address with the address specified in the NFT, everyone can verify the authorship and authenticity of this NFT.
When you create an NFT, you “sign” the transaction, essentially autographing your Instagram post or other digital content (similar to how an artist might sign a canvas to prove the artwork’s authenticity). So, if someone wants to purchase your Instagram post, they want to buy the NFT with your autograph on the digital file as proof that it is the original copy.