eNewsletter subcription - Form stuck on "Saving..."

1. The subscribe button doesn't work in this plugin. As you can see in the screenshot after pressing the subscribe button the form is stuck at saving. No new member has been added to the subscriber list.

I used this shortcode to generate this form.

[enewsletter_subscribe show_name="1" show_groups="0" subscribe_to_groups="4"]

2. The styles are missing from the generated form. How can I make it look nice? (I'm using divi theme)