Friends playing my CS problem

[Ermu]

I have a custom which is totally playable. I have played it through a lot of times.
It is a very internal map (not sure if that word is correct
Only my friends would be able to play this CS because it is of my school and it is in Danish.

Now, my friend wanted to play it on his computer, so I put the folder (it's called "OE") in a .rar file
And transfered it to his computer.
He used to be able to play the normal amnesia, but now when he has my folder in the custom stories folder, he suddenly can't play amnesia anymore. It comes up with the error:
FATAL ERROR: No sound device detected. Check OpenAl (something like that)

Now I've been searching on this, and we tried download the OpenAl sdk. He did what he had to do with it, and then he was able to open amnesia, but my custom story wasn't there.
Later on he tried again, and now he gets the fatal error again..

What should we do?

Do you have all the custom files you used in it in custom_stories/yourcs/? (ie. /maps/, /sounds/)