I live in Belgium, but I haven't the knowlegde of making a game and so on, so playtesting isn't for me I'm afraid!
We don't expect you to debug code or anything

Playtests are mainly for us to know if something is fun/easy/hard/repetitive/...
Another example: We already know how to solve every quest and puzzle coz we designed them.
It takes a new set of eyes, someone who doesn't know the solution to tell us if the puzzle is too easy or too hard.
If we find out that none of the playtesters know where to go after a certain part of the story, we know we have to add small hints to make it clearer.