I think they're trying to say Dulles was the head of the OSS station in Switzerland.
Yes, that is what he was. NOT the head of the OSS… not even close. The Bern office handled the caputliation of German forces in Italy. They had nothing to do with Berlin, Hitler, or the unconditional surrender of theNAZIs.
Go to https://upload.wikimedia.org/wikipedia/commons/1/11/German_instrument_of_surrender2.jpg to see the document.