Need ads.txt file whitelisting in DEV Hosting

A requirement for google adsense now is to add a file called ads.txt to the root folder of the site.

https://support.google.com/adsense/answer/7532444?hl=en-GB

Unfortunately on WPMU DEV hosting, when you add the file, it is not accessible to browsers and gives a 403 error.

Could we add ads.txt files to some kind of whitelist?