How can I use Jotform feedback button plugin for Wordpress?

You have to install the plugin, go to its settings, and input the form ID there. 

Here's our Jotform Feedback Plugin: https://wordpress.org/plugins/jotform-feedback-button.

Once the plugin is installed, go Settings > Jotform Feedback Button and configure the plugin as shown below:

Guide for WordPress.org:

https://www.jotform.com/help/324-A-Guide-to-Embed-Forms-for-WordPress-Users