Is giving a little bit of an informal interview for clubs a sin?

Recently I had an interview for a college club for a position that requires the person to be friendly and have a good connection among people. He/she must be a good people pleaser and can sell membership of the club. So I thought as per the job description I'll manifest myself as a friendly person (which I am in actuality). What exactly happened there, they judge my behaviour as an informal person . Now, maybe because of this I'll lose my deserving position for this. Tell me guys is it really that compulsory to be in the utmost formal appearance in an interview where the description requires you to be friendly? I mean seriously 😣😳