Using Aperture Exporter can be as easy as:
- Start Aperture
- Launch Aperture Exporter
- Click the Begin Export Button
- Select a destination for the library to be exported to
- Wait for export to complete
- Import the destination from step 4 into Adobe Lightroom or other manager such as Capture One
We even did a fun quick start video.
On a more serious note, you might also want to check out A Step-by-Step Process to Get Photos from Aperture to Lightroom CC/6 Using Aperture Exporter.
Current Version: 1.4.0
System Requirements: Mac OS X 10.7 or up to 10.14.x (Mojave). It is not compatible with MacOS 10.15 (Catalina) or above as Aperture is no longer able to run on those versions. A working installation of Aperture 3.x is required.
Snow Leopard users may want to check out AE V1.3.2 For Snow Leopard Users (OS X 10.6 64bit).