CNAME link: This documentation does not exist or has been deleted

I got a question about the link that i need to fill in as cname for my custom domain. Apidog give me the url https://347839.eu.apidog.com/ and that give me the result that is doest not exist or has been deleted. Is that because the custom domain is not validated yet? Or should is use (https://vplan.eu.apidog.com/). This is the Apidog Europe provided domain that i changed to vplan.

You need to set a CNAME in the domain host website. Once the custom domain is effective, you can access the published document through either the Apidog provided domain or the custom domain.
For more information, please refer to this document: Custom domain - Apidog Docs

But the error we now getting on https://347839.eu.apidog.com/ is correct? and that should work when we add that url to the domain host website

I would expect https://347839.eu.apidog.com/ to already work, just like https://vplan.eu.apidog.com

The CNAME in Figure 1 needs to be configured on the domain host website. Once configured, the effect of viewing the document through the custom domain will be consistent with the document effect in Figure 2.