I work with Safari and I can see the form here hidden link if I am logged in.
Then I see the only field in the form (email) and could submit it.
Please make sure:
- you are logged in
- you are using the latest Safari version
- If you want this form to be visible for non-logged in users then alter it's rights in Toolset > Access > Toolset Forms (hidden link), and ensure the "Post Forms Frontend Access" for the desired user role are adequately allowing access where required.