Entering Lounge with a guest flying on a different airline
I am booked on a ticket with KLM (flying blue) gold and have a friend, who will fly at the same time, but with Lufthansa, in a different flight.
The flying blue website says I can bring a guest to the lounge, but are there any requirements for this guest, e.g., a KLM ticket as well?
The location would be in Vienna, if it matters. Thanks!