When you add a new member to your Fulcrum organization, a user account is created. Each user will sign into their user account using the email with which they were added, and the password they set for themselves from the welcome email.
A user account can be invited to be a member/user of multiple Fulcrum organizations.
A user account should not be shared by multiple people.
An email address can only be associated with a single user account.
It is important to use a valid email address when adding new members, as each user will need to receive a welcome email to set their own password.