Answer
Doing Single Touch Payroll is easy with Lightning Payroll. Usually you only need to make sure there is an ATO Machine Credential installed on the machine on which you run Lightning Payroll.
If you already have your Machine Credential installed on your computer, you do not need to do anything else to link it to Lightning Payroll directly. Lightning Payroll will automatically find and recognise your Machine Credential.
The only other step is to make sure your Lightning Payroll program is up to date. To do this, click Check for updates now, at the bottom of the Lightning Payroll program. If an update is available, click Yes.
You are now ready to go.