What does the error message "form over quota" mean?

It can mean that you have set some limits on your forms and that these limits have been met, causing it to show such error.

In your case however it is shown because you have reached your account limits with the secure submissions.

Now since this seems to be the first time that this has happened for your account, I have reset the limits for the secure submissions (but we can do this only once).

Please do check the forms that you have embedded on your website and change their URL to a non secure code.

You can see here how to get the secure code: Get embed code for Secure Form

To get the non secure form, you need to use the same steps, just make sure to have that checkbox unchecked - no matter what embedding code you are using.

Once you do that you will start using regular submissions (which are limited to 100 per month for free plan, unlike secure that are limited to only 10).

Do note that if you do not change the links on your website, you will keep using secure submissions which we will not be able to reset for you, so you will need to wait for every first of a month to have the counter reset (as I just did for you this time).

Hope this helps, but do let us know if there is anything that we can assist you with and we would be happy to do so :)