Assuming the data is saved in a database you could create a total count function. You will obviously need to work on the query as its impossible to answer without knowing what your database looks like. If you aren’t saving the data, then theres no chance your going to get this to work.
Here is an example function
function userTotalSignupCount() {
global $wpdb;
$userTotalSignupCount = $wpdb->get_var("SELECT COUNT(id) FROM yourTable");
return $userTotalSignupCount;
}
Then you can call the function somewhere in a template like
$userTotalSignupCount = userTotalSignupCount();
echo $userTotalSignupCount;
Hopefully that will help you get going.
And if you just wanted to display total WordPress users.
<?php
$result = count_users();
echo 'There are ', $result['total_users'], ' total users';
?>