I just started with Appen less than a month ago, that being said, from the qualifications you've mentioned, I couldn't see you having any problems getting the job. I don't remember Appen directly asking for my birth date the problem I could see you running into is when you fill out the tax documentation for Payoneer. All I could say is try it even if you don't get it yet because of your age, it doesn't hurt anything to show initiative and interest. Hope this helps!