Genymotion Error: "Failed to load VirtualBox Engine" on Yosemite. VirtualBox installed

I have a 13" Macbook Pro with OS X Yosemite [8 GB RAM, Graphics Intel Iris Graphics 6100 1536 MB]. I am trying to setup Genymotion as an Android emulator. I first installed Oracle VirtualBox from https://www.virtualbox.org/wiki/Downloads [VirtualBox-5.0.0-101573-OSX.dmg] and then installed Genymotion from Genymotion [genymotion-2.5.0.dmg] for personal use. .

but I am getting the following error -

I checked all previous answers on StackOverflow and Google search results and did the following, but none of them solved the problem.

1.（a）

sudo /Library/Startup Items/VirtualBox/VirtualBox restart

or (b)

sudo /Library/Application\Support/VirtualBox/LaunchDaemons/VirtualBoxStartup.sh restart

Since my /Library/Startupitems/ was empty, I tried option (b).

2. Open VirtualBox->Preferences->Network , under " Host Only Network " I deleted the one listed. Under " Nat Networks " there is an active network called " NatNetwork " selected.

3. vboxmanage has been added to the path, nothing under hostonlyifs

Terminal:

$ which vboxmanage
/usr/local/bin/vboxmanage

$ echo $PATH
/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin: <others>

$ vboxmanage list hostonlyifs
## no output - prints nothing

These are what I found by googling. How do I get Genymotion to work in Yosemite?

{If possible, please provide a less technical solution, since I'm new to Mac, it might also help someone who is using Mac for the first time. I know this is not a new question on StackOverflow. But none of the previous posts helped me. }

thank you for your help.