I have a visually designed form for calculating the amount of training and a plugin for sending the form to the mail. I need to figure out how to transfer information about what the user has selected on the radio created by me and the amount in the WPForm form in order to submit a request.

In wpform radio, you need to specify class .wpforms-selected for radio, then they are activated.

I understand that it can be done much easier and better, but in this case we are working with what we have, unfortunately.

 <div class="btn-group" role="group" aria-label="Basic radio toggle button group">
    <input type="radio" value="0" class="btn-check" name="wpforms[fields][19]" id="wpforms-320-field_19_1" autocomplete="off" checked>
    <label style="border-bottom: 0px;" class="btn btn-outline-primary w-50" for="wpforms-320-field_19_1">Онлайн</label>
    <input type="radio" value="3000" class="btn-check" name="wpforms[fields][19]" id="wpforms-320-field_19_2" autocomplete="off">
    <label style="border-bottom: 0px;" class="btn btn-outline-primary w-50" for="wpforms-320-field_19_2">В классе</label>
</div>




<ul id="wpforms-320-field_19">
    <li class="choice-1 depth-1 wpforms-selected">
        <input type="radio" id="wpforms-320-field_19_1" name="wpforms[fields][19]" value="Онлайн" class="wpforms-valid" aria-invalid="false">
        <label class="wpforms-field-label-inline" for="wpforms-320-field_19_1">Онлайн</label>
    </li>
    <li class="choice-2 depth-1">
        <input type="radio" id="wpforms-320-field_19_2" name="wpforms[fields][19]" value="В классе" class="wpforms-valid" aria-invalid="false">
        <label class="wpforms-field-label-inline" for="wpforms-320-field_19_2">В классе</label>
    </li>
</ul>