This plugin connects WordPress with your ActiveCampaign software and allows you to embed your subscription forms on your site.
You need to be using ActiveCampaign email marketing software to use this widget. Create new subscription forms in the software by going to the "Integration" section, then they will be available through this plugin.
This plugin makes it much easier to do without requiring you to know which theme (or core WordPress) files to modify. Also, copying and pasting HTML into WordPress can often cause odd display issues (depending on your WordPress theme).
The same thing that would happen if they submitted it from another site: it redirects back to the ActiveCampaign confirmation message, or a custom URL if you have that set up for the subscription form in ActiveCampaign (modify your forms under the "Integration" section).
If you enable the "Ajax" option of the plugin settings, you can have the form submitted without the page reloading (so the viewer never leaves the page).
Yes, you would just make sure that your form settings (in ActiveCampaign) have the Opt-in confirmation setting checked.
Please make sure that your login information is correct, and that you have at least one Integration form already created in the ActiveCampaign system.