Embed form no longer free?

Could you please clarify the position on embedding forms for free. I have a client with a very low throughput and the free option for up to three apps is all that is needed. However it is useless unless the forms can be embedded in his site. Zoho Creator allows me to do it and initially it appears to work - it does not display a login - but it comes up with the error message 'Invalid entries found. Please correct and submit again' when I put data in. Is that a symptom of the need to upgrade?

If that is the case I know my client will not pay $25 per month. I respectfully suggest you would make more money if you set the entry subscription lower or made it a one-off payment.