Trying to export data

The main guide on export from online to desktop is here https://quickbooks.intuit.com/community/Reports-and-accounting/Export-data-file-from-QuickBooks-Online-to-Desktop/m-p/186302

Limitations are here https://quickbooks.intuit.com/community/Reports-and-accounting/Export-limitations-QuickBooks-Online-to-QuickBooks-Desktop/m-p/185940

You say you do not have the Export Data button, what version of QBO are you using? All 3 support export and even if you are logged in with other than IE11 the button should be there but give you an error when you click. However since you must be logged in with IE11 I would start with that. It is possible they removed the tool from view in non-supported browsers