When a brand sets up a campaign, they set requirements for the kinds of creators they want to be involved in their campaign. Requirements might include age or location. They might also be factors like followers on Instagram, or if you're badged as a Pin Collective member.
If you've just signed up for Popular Pays and your app says "We don't have any gigs for you right now," it doesn't mean that you've done anything wrong.
If there aren't any gigs for you, it might be that you don't meet the requirements of any current gigs. It might also mean that none of the gigs on Pop Pays are currently accepting applications, and one might open up soon.