This dropdown lets you select which field to use for your password field.
This field is where Memberium will temporarily store generated passwords. For example, if you use a password generation webhook in ActiveCampaign to generate a user’s password, Memberium will store that password in this selected field so that you can email it to the user.
Keep in mind that once the user logs into your site for the first time, Memberium will clear out the password field. This is to enhance and improve security.