The Aspiration Zero Credit Card credit limit is usually around $12,000 to start, according to forum posts, and some cardholders report limits as high as $40,000. Aspiration does not include any specific Aspiration Zero credit limit information in the card's terms, though.
For the most part, Aspiration Zero credit limits depend on each applicant's overall creditworthiness. Those with the highest income and best credit scores will generally be offered the highest starting credit limits.
That said, the Aspiration Zero Card credit limit that you start with isn't necessarily your credit line forever. You can ask to get a credit limit increase by calling the Aspiration customer service number on the back of your card, but it's best not to ask more than once a year.