Different account plans come with different download allowances. Check your account dashboard or subscription details to see how many downloads you have. If you hit your limit ("no more downloads available"), you may need to upgrade your subscription or wait until your allowance resets (if on a monthly plan). For example, upgrading to a higher tier will grant more downloads per month.
This article explains how to view your subscription status, what to do when the download limit is reached, and how to upgrade or extend your plan for more downloads.