Hey @nltnme003,
to make it short: on our marketplace we generate the traffic by setting up marketing campains ads. So you have nothing to do but to create good content that fits the interests of the visitors. Of course there are a lot of other partners on the marketplace doing the same.
In a shop on the other hand you have to generate the traffic by your own. You have to make sure that your targetgroup finds your shop by using various channels. Shop means more efort but maybe also more liberties and flexibility.
On our marketplace you will earn a fixed price for each product - you cant change the price. In your shop you can decide for what price you want to offer your designs.
Regarding your other question with the mugs and other products:
I had a short look into your account. You have only 2 designs uploaded yet. And for one of those you already switched on ALL products - so I dont get your question?
Be aware, that most time switching on all products for a design is not the best because the design has to fit to the product. If you switch on all you also have kids- and babies-products for example - together with an adult-design this combination could look very unprofessional for the customers so that they maybe buy nothing in the end.
Please try to find only fitting products for your desings.