To embed Jotform into Squarespace, you can follow these.
#1. Open Jotform > Click More > Publish form
#2. Click EMBED > COPY CODE
#3. Edit page where you want to add Jotform on Squarespace > Add a Code Block
#4. Paste your Jotform embed code
Note: this is the default message in edit mode, you can ignore it.
#5. Save and Preview the page. You will see.