<form action=""enctype="multipart/form-data"
          method="POST">
        {{form.hidden_tag()}}
<table>
{{ render_field(form.name, size=50) }}
    <tr class="submit">
        <td>
            <button type="submit">Report</button>
        </td>
    </tr>
</table>

@app.route('/users', methods=['GET', 'POST'])
def users():
    form = UsersForm()
    if form.validate_on_submit():

        output = user(name=form.name.data)

        return send_file(output, attachment_filename = f'UserReport_{name}.csv', as_attachment=True)

    return render_template('name', form=form)