The table wrapper is used to wrap responsive table markup. When adding responsive table snippet, you will have to create a table inside the snippet block in the WYSIWYG.
<table class="stacked">
<!-- table markup here -->
</table>
<table class="stack">
<thead>
<tr>
<td></td>
<th scope="col">Column 1</th>
<th scope="col">Column 2</th>
</tr>
</thead>
<tbody>
<tr>
<th scope="row">Row Header</th>
<td data-title="Column 1">Body</td>
<td data-title="Column 2">Body</td>
</tr>
<tr>
<th scope="row">Row Header</th>
<td data-title="Column 1">Body</td>
<td data-title="Column 2">Body</td>
</tr>
<tr>
<th scope="row">Row Header</th>
<td data-title="Column 1">Body</td>
<td data-title="Column 2">Body</td>
</tr>
</tbody>
</table>