When you make a Currensea transaction, we look at all the pending / uncleared Currensea transactions on your account. If sum of these exceed the overall limits on your account, then your transaction will be rejected with the Maximum Pending message.
To resolve this issue, you need to wait for a set of Currensea transactions to clear over upcoming days, to essentially free up the utilisation.
You can see the amount of pending transactions by tapping on the 'balance' at the top of the home screen on your app, or you can see the status of specific transactions if they appear in grey within the app. They will be marked as cleared over subsequent days.