I'm creating files on AI and saving them as PDF's as this is the format I need however whenever I then come to upload them onto another platform such as Etsy for example it greys out in my file and I am unable to upload it. Please help, I've been trying to work this out for ages. I can save it as a Picture file JPEG for example and it will allow me to upload this but the quality is not as good.
Not sure what you are asking. The supported file formats and their specifications are up to the discretion of the people running those platforms. this is nothing you can in any way override or enforce nor does it have anything to do with Illustrator.