function set_custom_pipedrive_app( &$crm ) {

    $crm->client_id     = 'XXX';
    $crm->client_secret = 'YYY';

}

add_action( 'wpf_crm_loaded', 'set_custom_pipedrive_app' );

function custom_pipedrive_auth_url( $url ) {

    $args = array(
        'client_id' => 'XXX',
    );

    return add_query_arg( $args, $url );

}

add_filter( 'wpf_pipedrive_auth_url', 'custom_pipedrive_auth_url' );