Hi @nsumit,
I have checked PayPal test form on my installation and it worked fine there so it seems that there’s something specific on your installation that is causing this.
Can you double check that the PayPal details you’ve entered in Forminator are correct?
It’s also possible that there’s a conflict on your site so could you perform a conflict test by disabling other plugins and switching to default WP theme to see if the button works after that?
If it does, activate them back one by one until the issue is back to see which one is causing it.
I suggest doing this test on a staging site, or if you don’t have one make sure to have a full backup ready before doing the test on live installation.
Cheers,
Predrag