JSFiddle - React, Tailwind, and code Playground

HTML

<input type="checkbox" id="checkbox1" name="checkbox1" class="required" />Please read the <a href="#">Terms and Conditions</a>
<input type="button" Text = "Submit" name="Order" />

JavaScript

var j$ = jQuery.noConflict();
j$(document).ready(function() {   
    var checkbox1 = j$('#checkbox1');
    var order = j$('input[name="Order"]');
    
    var verifyChecked = function() {
        if (checkbox1.is(":checked") === false) {
            order.attr('disabled', 'disabled');
        } else {
            order.removeAttr('disabled');
        }
    };
    
    verifyChecked();

    checkbox1.change(verifyChecked);
});