WP User Integration required ticket capability message: Add a custom message that includes a link to log into the website.

wp_user_restrict_ticket_option_message.php

<?php
//* Please do NOT include the opening php tag, except of course if you're starting with a blank file

add_filter( 
  'FHEE__EED_WP_Users_Ticket_Selector__maybe_restrict_ticket_option_by_cap__no_access_msg',
  'my_custom_no_access_message',
  10,
  4
);

function my_custom_no_access_message( $content, $tkt, $ticket_price, $tkt_status ) {
  $url = wp_login_url( get_permalink() );
  $content = $tkt->name() . ' becomes available if you log in to your account. ';
  $content .= 'You can <a href="'. $url .'" title="Log in">log in here</a>.';
  return $content;
}