Hi Ana,
For this, you need to change the access role of time-off page in plugin menu.
Use file appointment-calendar.php to change access role
// Time-Off Page
add_submenu_page( 'appointment-calendar', 'Time Off', 'Time Off', 'administrator', 'timeoff', 'dispaly_timeoff_page' );
// Update Time-Off Page
add_submenu_page( 'appointment-calendar', 'Update TimeOff', '', 'administrator', 'update-timeoff', 'dispaly_updatetimeoff_page' );
By default its access role is: administrator
WordPress has five pre-defined Roles: Administrator, Editor, Author, Contributor and Subscriber.
Set it according to your registered user’s role, then both plugin-menu-pages could be accessed by your users.
Thanks…
-Frank