1. Navigate to client's  Settings -->Import

2. Press QuickBooks Online - 

3. Once in QuickBooks, follow the prompts.

A - connect your client. Learn more
B - connect your firm. (In case you want to import accounting or BAS data relating to your accounting practice.)

4. You'll be navigated automatically back to LodgeiT and will see the connection is established.

Related Article:

Articles about 'QuickBooks Online' BAS

Importing Financial Statements from QuickBooks

Import BAS Values from 'QuickBooks Online'