Shamim's Plugins

Add following code in your theme’s (child theme’s if any) functions.php

add_filter( 'fep_directory_arguments', function( $args ){
    if ( ! empty( $_GET['fep-search'] ) && in_array( $_GET['fep-search'], [ 'Individual', 'Corporate' ] ) ) {
        $args['meta_query'][] = [
            'key' => 'group_type',
            'value' => $_GET['fep-search'],
        ];
        unset( $args['search'] );
    }
    return $args;
});

(untested).

if you search users with Individual or Corporate (case sensitive) then they will be searched with that meta.

Please let me know following

1. All users of client roles can view directory & add announcements?
2. Please send me capabilities of client role. (which plugin add this role? To know what i mean with capabilities please see https://codex.wordpress.org/Roles_and_Capabilities)

Please add following code in your theme’s (child themes if any) functions.php

add_filter( 'fep_admin_cap', function( $admin_cap ){
    return 'administrator';
});

If still it does not work then i need to debug your website with php code. You can deactivate all plugins except this and change theme to one of default theme (unmodified). Then test. Then activate one by one.
OR you can give me FTP access (only wp-content directory access is ok) so that i can debug your website. If you give me FTP access please use https://www.shamimsplugins.com/sensitive-information/

Did you check Front End PM PRO > Settings > Security > Can permitted users add Announcement from front end?

1. All users of client roles can view directory & add announcements?
2. Please send me capabilities of client role.

Do you have any custom code for this plugin?
Did you add that user as whitelisted in Front End PM PRO > Settings > Security?

Go to Front End PM PRO > Settings > Emails and unchecked “Send email to all users when a new announcement is published?”. This will prevent email sending when announcement is created. But there is no direct checkbox for message emails.

This plugin use wordpress core wp_mail function to send email, so that you can easily block email. There are some plugins also in wordpress directory to block emails when you are not in production.

add subject="{current-post-title}" in your shortcode

Please follow https://www.shamimsplugins.com/support/topic/show-all-replies-on-load/#post-11326