Well the documentation says that version should work (7.3+). Although I would probably look at upgrading to at least 7.4.
Unfortunately, sending forms can be difficult to troubleshoot. PHP for security reasons doesn’t display errors to the browser. Your hosting company might even have erRor logging turned entirety off. If they are logging errors you’ll need to find out where the error log fole is located.
Other than finding the error logs, I’d suggest you start a support request with @yabdab and in the meantime I’d double-checked the mail settings, make sure the mailbox works.
You might also check with the hosting company and find out what changes they might have made when it comes to sending mail. More and more hosts are tightening down on sending mail.