"Code" or "combination" are normally used for numeric or character inputs. So anything that is just numbers or simple characters, or both, and that is quite short is a code or combination. E.g. AB123C A password is usually something longer that might contain more recognisable sequences of letters. E.g. mypassword123 To be honest, we only really use the word "combination" when we are talking about more mechanical devices like padlocks, safes, suitcases etc. Hope that helps!

Here on the West Coast of the US, most people would say, "Can I have the code for the restroom?" or "... to the restroom?".

You would want the key for the bathroom

For the most part, a password is used to describe a word said to gain access to somewhere. You might use a password to log into your computer, or to gain access to an area. At Starbucks, you likely are not using a password, you would use a combination on the lock. Password implies the second part of the word, a word, or a phrase. A combination/code refers to numbers.