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Update your Settings → Reading → Homepage settings.

Seems like the developer of your theme is using 3rd party framework or plugin as get_field() is not an in-built WordPress function. Great to hear that everything has worked out.

Probably, your custom fields have some other names. You will need to get them.

Try this code (it is not safe, but should output fields if they do exist):

$service_used = get_post_meta(get_the_ID(), 'service_used', true);
$service_url = get_post_meta(get_the_ID(), 'service_url', true);
echo '<a href="' . $service_url . '">' . $service_used . '</a>';

Your WordPress database is configured to work with kr8bureau.at site. Look at this guide or replace strings in database manually.

Post contents of item-video.php & loop-actions.php to pastebin.com, please.

Yes, there is a way, but it is accessible only if you are good with PHP coding and know WP core well. I don’t think there is good free alternative.

Why don’t you create a separate category for Wedding Section posts and grab them on your page with a loop?

Sorry, my bad:

$service_used = get_post_meta(get_the_ID(), 'service_used', true);
$service_url = get_post_meta(get_the_ID(), 'service_url', true);
if($service_used && $service_url) :
    echo '<a href="' . $service_url . '">' . $service_used . '</a>';
endif;

Yes, there is a good plugin for posting from the site.

I am not sure pre-baked solutions for your situation exist. Try hiring WordPress specialist (developer) that would do that for you, because it requires some levels of protections (least safe way: robots.txt + cookies for each buyer).

Oh, I guessed your fields ??
Try that code and report if it works, please.

Safe example of code:

$service_used = get_post_meta(get_the_ID(), 'service_used_field', true);
$service_url = get_post_meta(get_the_ID(), 'service_url_field', true);
if($service_used && $service_url) :
    echo '<a href="' . $service_url . '">' . $service_used . '</a>';
endif;

I don’t know where you are trying to insert those fields. Also, I don’t know IDs of your fields (Service Used or Service URL are not correct ones, they shouldn’t be separated by spaces).

Check this guide.