To Jailbreak iOS 8.4 on Mac, all you have to do is:
- Always back up your data
- Disable Touch ID, pass code, and find my iPhone
- Turn on Airplane Mode
- Download PP Jailbreak V2.0
- Connect your iDevice and run the jailbreak tool
- Uncheck the bottom checkbox and hit the Jailbreak button
- Click continue and wit for the process to end
- One the green checkmark appears, your device well reboot
- Turn off Airplane Mode and then open Cydia
- Done !!
That's it, you are now running the Untethered Jailbreak on your iOS 8.4 iDevice via Mac devices, and can enjoy even more customizations and tweaks.