Let me guide you on exporting your customers from QuickBooks Online to VarStreet.
Here's how:
Go to Settings, and select Export Data.
Go to the Lists tab.
Ensure to toggle only Customers.
Click Export to Excel.
After downloading the file, you can manually upload it to your VarStreet account.
You'll need the customer lists in Excel format if you're referring to exporting customers from VarStreet to QuickBooks Online. Ensure it is in the correct format that QuickBooks uses. Then, import it to QuickBooks Online.