Well, there are many methods you could use.
The easiest way for you to do this is using VCE to set a specified variable of a player, which the door then checks, and outcomes determine what happens
Some Random Brick
[0] [Onactivate] [Client] [VCE_Modvariable] [Password] [Set] [1234]
Door
[0] [Onactivate] [Client] [VCE_Ifvariable] [Password] [==] [1234] [1 1]
[1] [Onvariabletrue] [Door] [Toggle]
But, if you want to actually type in a password, you could use event mods like CMD events or any one of the onplayermessage-like-events which come with some outputs to test if the password is correct, or you could get the password mod that adds some events specific for passwording for things like doors.