Can't Verify Google Property

I am trying to verify my site http://studeren-in-australie.nl/

It is running as a sub-domain in a multisite network. I use domain mapping.

I have tried all different way(Meta tags, HTML file, Analytics) however no matter which one I try, they all come back with the following message:

Verification failed for http://www.studeren-in-australie.nl/. Your verification file returns a status of 404 (Not found) instead of 200 (OK).

I have checked my site with the tool: https://httpstatus.io/

I can’t see any errors or figure out why the page is not getting verified.

Any assistance would be very much appreciated.