What does "Conversion linker tag not found in container" mean in GTM (Google Tag Manager)?

When I tried to set up the Google Ads remarketing tag in GTM, I got the message "There is no conversion linker tag in the container." I wondered what a conversion linker was, so I looked it up!

What is a conversion linker?

This is a service that measures click data in order to measure accurate conversion information.
This is a new GTM service that was introduced as a countermeasure to the fact that accurate conversion data can no longer be measured on Apple's OS due to security measures.

By setting up a conversion linker, you can accurately measure user behavior across sites. This is a service you'll want to set up when running web ads.

How to set up a conversion linker

The following explanation assumes that you have already set up Google Tag Manager.

Add new tag

First, add a new tag.

You can give it a descriptive title. Then click the pencil to proceed with the settings.

Configure the conversion linker

There is a conversion linker tag, so click on it.

Setting up triggers

Select All Pages

Since we want to target all pages, select All Pages in the tree settings.

Completed

Once you have set it up like this, click [Save] and then [Publish] to complete the setup.