You can extract images with The Unarchiver, but no need to do this, if you will use ApplePi Baker.
After burning image to SD-Card reject both partitions via finder.
Put SD-Card in your device and power it up.
Before you can login via ssh, it will take some time. Installation will automatically reboot your device 2 times. So be patient and watch green led on your device.
Now you can log in via ssh by typing <ssh root@IPaddress> and DietPi will automatically update to last version.
Once completed, press enter to reboot the system. You can log back in again to resume initial setup.
I have followed the procedure that you outlined and I flashed Dietpi image to the SD Card using Etcher.
You said “After burning image to SD-Card reject both partitions via finder.”
What do you mean by “reject both partitions via finder”?
Using finder I can see that there are many files in the root directory and also two folders (a folder named “dietpi” and another folder named “overlays”). Each folder has files in it. Again, what do you mean by “reject both partitions via finder”?
I just checked using the Disk Utility app and can only find one partition that is named “boot”. It may be possible that since I used Etcher, it only created one portion.
I will continue following the steps that you mentioned earlier and will post my results.