Disable the button unless a checkbox is ticked


I am using a WPExplorer Total theme for my website. I am making a page that needs to have a Terms and Conditions agreement text in a build-in window, a checkbox and a button that is disabled and becomes clickable only after the checkbox is ticked and these parts are not available with the theme but the theme has free HTML block and free JS block that can be used to add any custom content.
Here is the page that needs customization : https://www.gaiax.co.jp/test/ and here are the parts that need to be included in the page : https://community.gaiax.co.jp/