Sign-in button is not working on Safari on MacBook Pro

I usually have no problem logging into my account, but when I tried to log in using Safari on MacBook Pro, I have no access.  After entering my username and password, the enter button does not work.  It's like my options are limited from there.  I an log on at the library and using my Galaxy S6, but no on my sister's Mac.  What can be the problem and how do I fix it?  

So, basically you are not getting any error, it is just the "Sign-in" button not working using Safari on MacBook Pro, correct?

Unfortunately, I don't have a MacBook Pro devices to test with, but I have forwarded this to our developers to get further help. You will be updated via this thread.

That is correct.  But when I downloaded Firefox, I had no problems.  It's just problems with the Safari.
...

Please go to My Forms page, this URL: https://www.jotform.com/myforms. Click the Login button on the top and do it from there. Check if you can.