JSFiddle - React, Tailwind, and code Playground

HTML

<div class="form">
    <form>
      <div class="field">
        <label for="username">Name</label>
        <input id="username" name="username" type="text" value="Vorname Nachname">
      </div>
      <div class="field">
        <label for="email">E-Mail Adresse</label>
        <input id="email" name="email" type="email" value="[email protected]">
      </div>
      <div class="field">
        <label for="password">Handicap</label>
        <input id="password" name="password" type="text" value="z.B. 3">
      </div>
      <div class="field">
        <label for="rpassword">Gäste</label>
        <input id="rpassword" name="rpassword" type="text" value="z.B. 2">
      </div>
      <div class="checkbox">
        <input id="check" name="checkbox" type="checkbox">
        <label for="checkbox">
          Ich bin einverstanden dass mich die Leute kontaktieren
        </label>
      </div>
      <input type="submit" name="anmelden" class="button" id="btncheck" value="Anmelden" />
    </form>
  </div>

CSS

.form input[type="checkbox"] label {
  background: #000;
  height: 30px;
  border: none;
}
.form .button {
  cursor: pointer;
  display: block;
  background: rgba(46, 204, 113,1.0);
  width: 180px;
  margin: 0 auto;
  margin-bottom: 40px;
  padding: 16px 0;
  border: none;
  border-radius: 100px;
  color: #fff;
  font-family: 'Open Sans';
  font-size: 16px;
  font-weight: 600;
  text-transform: uppercase;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: 0.2s linear;
}
.form .button:hover {
  background: rgba(46, 204, 113,0.5);
}

JavaScript

$('#btncheck').attr("disabled",true);
$('#check').click(function(){
    $('#btncheck').attr("disabled",!$(this).is(":checked"));   
})