The submit button is a form field (type submit button) which you have to create by yourself.
Joomla 5 Notice
We are pleased to announce that as of January 29, 2024, all of our Joomla extensions are compatible with Joomla 5.
For all who are still updateing from Joomla 3 to Joomla 4: Joomla 4 Migration instructions are available here:
There is now a separate Documentation for Visforms for Joomla 4 and for Visforms for Joomla 5!