Hi,
The FedEx shipping provider is expecting both DeliveryAdress and DeliveryAddress2 filled in - it should only validate DeliveryAdress, or as another option do an OR clause. Although DeliveryAddress is the main field which should always be populated.
https://github.com/dynamicweb/Shipping.FedEx/blob/d7409e520b2211c16d6a5319b479fcf5197a44c4/src/Service/RateRequestCreationHelper.cs#L92
BR Mario