My square will not accept master card citi bank and clients card is good on they're end

[Buildershouse]

I just made my square account and it will not accept credit card

master card from city bank

[VanKalkerFarms]

there isn't anything different about credit cards so if one works all will that have visa, MasterCard, discover, and Amex.  if you just set up your account it could be you haven't finished and your account isn't approved to accept credit cards.