FlexClip provides 3 plans for you: Free, Plus, and Business. Every plan has its limits. You can check the details on the Pricing page.
If your video elements have exceeded your current plan limits, you will be asked to upgrade to a higher plan.
Click the Export button to check the limit you have exceeded. Please re-edit your video following the instructions, or upgrade your plan, and then you can export your project successfully.
Here is an example for your reference:
