There are no stipulations on the number of designs you can submit to an individual competition. So feel free to submit more than one per competition. This could also better your chances of being picked as one of the top three, or even two of the top three..
As a designer you will need to have the facility to create Adobe Illustrator (AI) files at a high resolution format.
Submitting an attempt to competitions can be in the form of a JPG, PNG or GIF file.
If you are the competition winner you will be required to upload the following: A Vector PDF, An Adobe Illustrator (AI) file, A Transparent PNG (1000 x 1000 px) and A Colour JPG (1000 x 1000 px).
Following submission and review you will be paid your prize money via Stripe or PayPal.