Unable to reset forgotten password in Mac

Hi

I have a Mac that I don’t use on regular basis. Today I could not remember my password, and the PW hint didn’t make sense. There were no options to reset a forgotten password, only to enter a recovery key. I had never heard of that so after a great deal of fuss and ado, I created one on my iPad but the Mac laptop won’t accept it. I’m not sure what to do from here. Any suggestions?

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