Log into the site using the username & password given in the "Access Details" message.
Hover over Member Dashboard to bring up "Edit My Profile" and click it.
Then scroll down to Account management and set new password button. Enter the password you want, copy it down and save it.
Then scroll to the bottom and click the Update Profile Button.
Hover over your profile picture in the upper Right Hand Corner to get the log out button.
Log out, log back in using your new password to make sure it works.