I would suggest you follow some tutorials or get a developer, as this is custom development, and its not something we can teach or do for you.
I can only assist a little:
1. in that document, there is this code:
function my_cptui_add_post_types_to_archives( $query ) {
// We do not want unintended consequences.
if ( is_admin() || ! $query->is_main_query() ) {
return;
}
if ( is_category() || is_tag() && empty( $query->query_vars['suppress_filters'] ) ) {
// Replace these slugs with the post types you want to include.
$cptui_post_types = array( 'my_post_type', 'my_other_post_type' );
$query->set(
'post_type',
array_merge(
array( 'post' ),
$cptui_post_types
)
);
}
}
add_filter( 'pre_get_posts', 'my_cptui_add_post_types_to_archives' );
Add the code to your site, this doc explains how:
https://docs.generatepress.com/article/adding-php/
2.
in that code you will see this line:
$cptui_post_types = array( 'my_post_type', 'my_other_post_type' );
where it says my_post_type and my_other_post_type change them to the slugs of your CPTs.