If you have that question I might be able to answer it...
Check the notepad file attatched to this thread and it will guide you throughout the process on how to install DayZ, ACE or any other mod...(Note: The notepad file was not created for this purpose it was for a steam user so some details might be incorrect if you have another version)
To install ACRE its a little bit different and its not stated in the .txt file... this is how you do it:
Repeat step 10 of the notepad file Now its where it gets tricky... On the bottom right of Play with six you will see a search bar right under ´´Add Mods to selected set`` in that search bar you will type ACRE. Now you press the System(2) that will appear underneath. Now press ACRE and it will link you to a webpage... What you have to do now its press ´´Download or play with six`` on that webpage that opened. You just need to press it once it seems like nothing happened but open your play with Six and you will see a message... Press Ok on that message and ACRE should be on your mods list... All you got to do now its press install like you would do to any other mod.
Note: For ACRE to work propperly you will have to restart Play with Six and launch TS3 as Admin that will stop any ingame problems.
P.S.: On the .txt folder it is written some stuff about directories witch involve Steam (step 9), if you did not buy the game through steam simply look on your hard drive for the Arma 2 Operation Arrowhead folder and replace it by the steam directory on the Play with six.