Mixing your favorite laundry detergent in a bucket of hot water and scrubbing your awning is a safe way to clean the fabric without damaging it.
Vinegar will remove dirt and mildew while killing mold spores and other bacteria that may be on the awning. Additionally, vinegar is safe for the fabric.
A gentle dish washing detergent such as Palmolive or Dawn is a safe cleaning agent for your fabric awning.
Basic upholstery cleaner that you can find in any store that sells cleaning products is good to use on a fabric awning.
Mix baking soda with a small amount of water to form a paste and scrub your awning with it. Baking soda cleans and refreshes without damaging the fabric, and rinses away clean.