What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
You must be referring to this step in the user guide -Adding-Form-to-Squarespace
at Step #5
Did you follow the user guide step by step?
The "Add Block" option is suppose to be available after you create a new Page.
Click on the new page and go to Edit Mode -- that should make the "Add Block" option available.
If you can also share to us the URL of your Squarespace website where you have used your jotform http://www.jotform.us/form/43236633536152, we will be able to provide with more suggestion.
Hope this help. Inform us if you need further assistance on this.