Authentication error basically means “wrong login details.” Most of the time, it’s caused by incorrect Company File login. MYOB account login is normally your email address, and company file login is by default just “Administrator” with no password.
If your Company File login/password combination is incorrect, you will always see “Authentication Error” when invoicing or importing data from MYOB.
What’s a “Company File”?
As a business owner, you can have more than one company, or branch offices, in your MYOB account, they are separate company files. See more here: https://goo.gl/aoVI9l
What’s my Company File login?
The default username is “Administrator” and the default password is blank, but if you have changed it or you cannot remember, you need to contact MYOB. See more here: https://goo.gl/cdybKs
Where do I enter this login?
In your Geo account, under Settings > Company Account > Integration, click on MYOB’s “Disconnect” button. A pop-up will appear, showing your company file name and login. Change them to the correct combination and click Save. See more here: https://goo.gl/61I9MV