Hi I cant install it on KSP v1.2.2 on my MAC.
I Copied the Stable Version of Mechjeb2 to the GameData directory.
But if i start a rocket there is no additional Gui from Mechjeb.
What i did wrong?

Edit: I write something from add AR202 to a ship. But how can i do this?

Thanks for help.

In the editor part list you should find the AR202 part and add it to your ship.

If you do not want to add part for Mechjeb to work then you have to also install this mod
http://forum.kerbalspaceprogram.com/index.php?/topic/88726-mechjeb-embedded-universal/&page=1

Thanks this Works.