Checkbox obrigatória ao apertar o botão

Eu gostaria de colocar uma checkbox obrigatória em html abaixo do botão de pagamento do meu site, gostaria que a pessoa só conseguisse continuar a compra se marcasse os termos de uso, caso contrário ele notifica que a pessoa não marcou a checkbox. Já tentei de tudo, não consigo, sou novo na área.

Meu botão de comprar:

            <button
         onclick="comprar('LINK DE PAGAMENTO')"
         class="plans-button"
         klickart-edit-not-highlight=""
         klickart-edit-link-type="default"
         klickart-edit-link-href-klickbox="#"
         klickart-edit-link-href-faq-question="#"
         id="klickart-linkikl6qk5g77k00"
         style="background-attachment: scroll; background-color: rgb(255, 64, 64);"
        >
         <span><b class="medium-b">QUERO ESSE PLANO!</b></span>
        </button>

Porém eu gostaria de colocar a checkbox abaixo do botão, nessa posição:

O código dessas escritas abaixo do botão é esse:

      <footer class="plans-info" id="klickart-collection-2cimijo2l8k000">
   <div class="info-item">
    <span class="icon-footer">
     <svg klickart-edit-icon="svg" enable-background="0 0 512 512" fill="#c0c0c0" viewbox="0 0 512 512">
      <path
       d="M436.064,77.014c-48.238-48.248-112.377-74.809-180.6-74.809c-68.221,0-132.36,26.561-180.599,74.809C26.623,125.25,0.056,189.388,0.056,257.61c0,68.223,26.567,132.36,74.809,180.597c48.238,48.237,112.378,74.807,180.599,74.807c68.223,0,132.362-26.57,180.6-74.807c48.242-48.237,74.809-112.375,74.809-180.597C510.873,189.388,484.305,125.25,436.064,77.014z M490.314,257.61c0,60.436-22.954,115.609-60.594,157.274L98.189,83.355c41.664-37.642,96.837-60.596,157.274-60.596C384.96,22.759,490.314,128.117,490.314,257.61z M20.615,257.61c0-61.677,23.913-117.868,62.938-159.818l331.726,331.733c-41.95,39.024-98.139,62.937-159.815,62.937C125.969,492.462,20.615,387.104,20.615,257.61z"
      ></path>
     </svg>
    </span>
    <span>Cancele seu plano <b class="medium-b">mensal</b> a qualquer momento e sem compromisso.</span>
   </div>
   <div class="info-item">
    <span class="icon-footer">
     <svg klickart-edit-icon="svg" fill="#c0c0c0" viewbox="0 0 512 512">
      <path
       d="M507.4 351.5l-64.6-64.6 10.7-12.3c8.2-9.5 12-25.8 8.7-37.9l-4.3-15.7c-1.6-5.7-1.6-16.5 0-22.2l4.3-15.7c3.3-12.2-0.4-28.4-8.7-37.9l-10.7-12.3c-3.9-4.5-8.6-14.2-9.6-20l-3-16c-2.3-12.4-12.7-25.4-24.2-30.4l-14.9-6.5c-5.4-2.4-13.9-9.1-17.3-13.8l-9.6-13.1c-7.1-9.7-21.6-16.9-33.7-16.9h-0.9l-16.8 0.7c-0.2 0-0.5 0-0.7 0 -6.1 0-15.8-2.3-20.8-5l-14.4-7.7c-5.4-2.9-12.3-4.5-19.4-4.5 -7.1 0-14 1.6-19.5 4.5l-14.3 7.7c-5 2.7-14.6 5-20.7 5 -0.3 0-0.5 0-0.9 0l-16.5-0.7c-0.3 0-0.7 0-1 0 -12.2 0-26.7 7.3-33.8 16.9l-9.6 13.1c-3.5 4.7-11.9 11.5-17.3 13.8l-15 6.5c-11.5 5-22 18.1-24.2 30.4l-3 16c-1.1 5.8-5.8 15.5-9.6 20l-10.6 12.3c-8.2 9.5-12 25.8-8.7 37.9l4.3 15.7c1.5 5.7 1.6 16.5 0 22.2l-4.3 15.7c-3.3 12.1 0.4 28.4 8.7 37.9l10.7 12.4 0.2 0.2L7.8 351.5c-5.9 6-8.3 14.2-6.3 22.1 2 7.9 8 14 16.1 16.5l64.5 19.2 19.2 64.5c3 10 11.8 16.8 22 16.8 6.2 0 12.1-2.5 16.6-7l77.9-78c2.3 0.7 4.3 1.5 5.8 2.3l14.4 7.7c5.4 2.9 12.3 4.4 19.5 4.4 7.2 0 14.1-1.6 19.4-4.4l14.4-7.7c1.6-0.9 3.8-1.7 6.2-2.4l78.1 78.1c4.5 4.5 10.4 7 16.6 7 10.2 0 19-6.7 22-16.7l19.2-64.5 64.5-19.2c8.1-2.4 14.1-8.6 16.1-16.5C515.7 365.7 513.3 357.5 507.4 351.5zM125.1 460.7l-19.8-66.3c-1.1-3.7-4.6-7.3-8.3-8.3l-66.4-19.8 52.2-52.2 1.6 8.9c2.3 12.4 12.7 25.4 24.2 30.4l15 6.5c5.4 2.3 13.8 9 17.3 13.8l9.6 13.1c6.6 9.1 19.9 16 31.6 16.8L125.1 460.7zM278.9 384.8l-14.4 7.7c-1.7 0.9-4.3 1.4-7.1 1.4 -2.8 0-5.5-0.5-7.1-1.4l-14.4-7.7c-1.4-0.7-2.8-1.4-4.2-1.9 -5.9-2.5-13.3-4.5-20.2-5.4 -3.1-0.5-6.1-0.7-8.8-0.7 -0.4 0-0.8 0-1.1 0h-0.6l-16.5 0.7h-0.2c-4.1 0-10.3-3.1-12.6-6.2l-9.6-13.1c-6.2-8.5-18.5-18.3-28.1-22.4l-14.9-6.5c-3.7-1.6-8.2-7.2-8.9-11.1l-3-16c-0.7-3.9-2.2-8.5-4.2-13.3 -3.1-7.4-7.3-14.3-11.4-19l-0.4-0.5 -10.3-11.9c-2.6-3-4.2-10-3.2-13.9l4.3-15.7c2.7-10 2.7-25.8 0-35.9l-4.3-15.7c-1-3.9 0.6-10.9 3.2-13.9l10.6-12.3c6.9-7.9 13.7-22.1 15.6-32.4l3-16c0.7-3.9 5.2-9.5 8.9-11.1l15-6.5c9.6-4.1 21.9-14 28.1-22.4l9.6-13.1c2.3-3.1 8.5-6.2 12.5-6.2h0.3l16.3 0.7c0.6 0 1.2 0.1 1.8 0.1 10.3 0 24.5-3.5 33.1-8l14.3-7.7c1.6-0.9 4.3-1.4 7.1-1.4 2.8 0 5.5 0.5 7.1 1.4l14.4 7.7c8.6 4.6 22.8 8.1 33.1 8.1 0.5 0 0.9 0 1.4 0h0.3l16.6-0.7h0.2c4 0 10.2 3.1 12.5 6.2l9.6 13.1c6.2 8.4 18.5 18.2 28.1 22.4l14.9 6.4c3.7 1.6 8.2 7.2 8.9 11.1l3 16c1.9 10.3 8.7 24.5 15.6 32.4l10.6 12.3c2.6 3 4.2 10 3.2 13.9l-4.3 15.7c-2.7 10.1-2.7 25.9 0 35.9l4.3 15.7c1 3.9-0.6 10.9-3.2 13.9l-10.3 11.8 -0.4 0.5c-6.8 7.9-13.7 22.1-15.6 32.4l-3 16c-0.7 3.9-5.2 9.5-8.9 11.1l-14.9 6.5c-9.6 4.1-21.9 14-28.1 22.4l-9.6 13.1c-2.3 3.1-8.5 6.2-12.5 6.2h-0.4l-16.3-0.7c-0.5 0-1.1 0-1.7 0 -8.7 0-20.4 2.4-29 6.1C281.6 383.4 280.2 384.1 278.9 384.8zM418.2 386c-3.7 1.1-7.2 4.6-8.3 8.3l-19.8 66.4 -57.2-57.2c11.6-0.9 24.6-7.8 31.1-16.8l9.6-13.1c3.5-4.8 11.9-11.5 17.3-13.8l15-6.5c11.5-5 22-18.1 24.2-30.4l1.7-9.3 52.6 52.6L418.2 386z"
      ></path>
     </svg>
    </span>
    <span>Satisfação garantida!</span>
   </div>
  </footer>
 </div>
</section>

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<input type="checkbox" name="myName" id="myId" required> Li e Concordo com os Termos de Licensa do Site
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