You cannot export online data to mac desktop at this time. Export from QBO ONLY works with IE11 AND QBDT for PC.
The other direction, mac to online is supported.
Beg, borrow, steal a friend's PC
Download free trial of QBDT 2019 to friend's PC
Export online data to friend's PC
IN QBDT 2019 for PC create a mac version company file and save to removable media
On your mac install the new mac version company file
Dell sells a small laptop that meets minimum specs to run QB for right now only $200