I can understand why it's difficult for you, Alex.
If you read the first two posts in this thread closely, you might find some answers to your questions. For example, you cannot post an arrangement if the arranger has not been dead for 70 years - even if the composer has.
We all know that there are many sites that share copyrighted material, but that's usually illegal. We use French copyright laws here (Mr. Delcamp is in France), and they are some of the strictest in the world.
If you ever have any questions about a particular piece, simply send a personal message to one of the moderators and we'll answer as best we can.
Thanks for asking!