Working with Luminar Flex through Aperture is very similar to the way it behaves with Lightroom Classic CC. To exchange a file from Aperture to Luminar Flex, follow these steps:
Make sure Apple Aperture is open.
Choose your image(s) in Aperture from the Library that you want to work on with Luminar Flex.
Choose Photo > Edit In > Luminar Flex... or right-click on the Image and select Edit In > Luminar Flex...
A new image is created and sent to Luminar Flex.
Make any edits or adjustments as needed in Luminar Flex. Use Luminar Looks or Workspaces to speed up your editing workflow.
When done, click the Apply button to send the adjusted image back to Aperture.