JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/css/bootstrap.min.css">
<div class="application-project">
  <div class="container">
    <div class="row">
      <div class="col-md-6 form-group">
            <div class="file-upload">
    			<label>
    			    <div class="form-file-box">
    			        <span class="status">Выберите файл</span>
    			    </div>
    				<input id="files" type="file" name="files[]" value=""  />
    			</label>
    			<div id="my-file-name"></div>
	        	<div id="my-file-size"></div>
			</div>
        </div>
        <div class="col-lg-12 form-group">
    		<div data-add='<div class="col-md-6 form-group"><div class="file-upload"><label><div class="form-file-box"><span class="status">Выберите файл</span></div><input id="files" name="files[]" value="" type="file" /></label><div id="my-file-name"></div><div id="my-file-size"></div></div></div>' class="button-file"><span><i class="fa fa-plus" aria-hidden="true"></i> Добавить еще файл</span>
    		</div>
    	</div>
    </div>
  </div>
</div>

CSS

.application-project {
  background: #ececec;
  margin: 3rem auto;
  display: block;
  width: 800px;
  padding: 3rem 2rem;
}
.application-project .h4 {
  font: 600 16px/16px Helvetica,Arial,sans-serif;
  color: #2C3E50;
  margin: 2rem 0 1rem 0;
}
.application-project .h4.form-title {
  color: #16A085;
  padding: 0 0 1.3rem 0;
  border-bottom: 1px solid #16A085;
}
.application-project label {
  display: block;
  font: 300 16px/16px pragmatica,Helvetica,Arial,sans-serif;
  padding: 0;
  margin: 0.8rem 0;
}
.application-project label span.sure,
.form-information span.sure {
  color: #C0392B;
}
.application-project .select,
.application-project .select-tags {
  width: 100%;
}
.application-project .select2-selection {
  border: 1px solid #c3d3e4;
  box-shadow: 0 1px 1px 1px #ececec inset;
  border-radius: 4px;
  font: 300 15px/15px pragmatica,Helvetica, Arial, sans-serif;
  height: 35px;
  padding: 0.4rem 0 0 0.3rem;
}
.application-project .select2-selection .select2-selection__arrow b {
  border-color: #2C3E50 transparent transparent transparent;
  margin-left: -9px;
  margin-top: 1px;
}
.application-project input,
.application-project textarea {
  font: 300 15px/15px pragmatica, Helvetica, Arial, sans-serif;
  border: 1px solid #c3d3e4;
  border-radius: 5px;
  margin: 0;
  box-shadow: 0 1px 1px 1px #ececec inset;
  width: 100% !important;
}
.application-project input {
  height: 33px;
  padding: 0 1rem;
}
.application-project textarea {
  padding: 1rem;
}
.application-project .button-file span {
  color: #16A085;
  font: 600 16px/16px Helvetica,Arial,sans-serif;
  display: inline-block;
  cursor: pointer;
  padding: 0.2rem 0;
  border-bottom: 1px dashed;
  margin: 1rem 0;
}
.application-project .button-file span i {
  font-weight: normal;
  font-size: 15px;
  color: #2C3E50;
}
.application-project .file-upload {
  position: relative;
  overflow: hidden;
  width: 100%;
  height: 65px;
}
.application-project .file-upload label {
  display: block;
  position:...

JavaScript

$(document).ready(function () {
  // Форма обратной связи | Статус файла
  $('body').on('change', 'input[name="files[]"]', function(){
    if ($(this).val() != '') {
      $(this).prev().addClass('disabled');
      $(this).prev().find('.status').html('Файл выбран');
    }
  });
  // Форма обратной связи | Добавить еще один файл
  $('.button-file').on('click', function() {
    $(this).parent().before($(this).data('add'));
  });
  // Форма обратной связи | Загрузка файла 
  $('input[name="files[]"]').on('change', function() {
    try {
      var file = document.getElementById('files').files[0];
      if (file) {
        var fileSize = 0;
        if (file.size > 1024 * 1024) {
          fileSize = (Math.round(file.size * 100 / (1024 * 1024)) / 100).toString() + 'MB';
        } else {
          fileSize = (Math.round(file.size * 100 / 1024) / 100).toString() + 'KB';
        }
        document.getElementById('my-file-name').innerHTML = 'Имя: ' + file.name;
        document.getElementById('my-file-size').innerHTML = 'Размер: ' + fileSize;
      }
    } catch (e) {
      var file = document.getElementById('my-file').value;
      file = file.replace(/\\/g, "/").split('/').pop();
      document.getElementById('my-file-name').innerHTML = 'Имя: ' + file;
    }
  });
});