No — you absolutely do not need to be a professional artist. theprintspace is open to everyone, from people printing their very first piece to established professional artists, photographers, galleries and institutions.
If you simply want high-quality prints of your own images — whether that's a single photograph for your wall or a body of work — you can order online, and create a free account whenever you'd like your files stored for easy re-ordering.
If you want to sell your art, you can set up a free account and start building print products at your own pace; there's no minimum experience, output or sales history required. There are also plenty of guides on file preparation, paper choices and marketing to support you as you grow.
In short: beginners and professionals are equally welcome, and you can start as small as a single print.