There are two separate logins when connecting MYOB AccountRight and Link4. These are:

(1) Your AccountRight login using your email address.

(2) The company file access login.

(1) Selecting the appropriate company file for the company you want to connect to Link4. 
(2) Entering “Administrator” as your username. 
(3) Leaving the password field empty, and clicking "Authenticate" button.

Make sure that the "Company File" field is not empty. If it is, please see this help page for information

(1) Open MYOB AccountRight and select "Setup" -> "User Access."

(2) Select the "Administrator" user ID.

(3) Whether or not the "This user will sign on with a my.MYOB account" or the "Invite user to be an online administrator" this box is ticked. Enter the relevant password/passwords, as they will reset during this process (you will be able to change them back).

(4) Untick the "This user will sign on with a my.MYOB account" box. You may now change the password for the Administrator account.

(5) After changing the password, click save.

Log back in to Link4 and try reconnecting your company file. The website will redirect to your Link4 dashboard if the authentication is successful.

Afterwards, you may again tick the "This user will sign on with a my.MYOB account" box in MYOB. Enter the appropriate email address and tick the "Invite user to be an online administrator" box. Finally, click "Save and Invite user."