Ads.txt support

Hi, I need help with setting up my advertising app-ads.txt

http://dwayneblundell.epizy.com/app-ads.txt

using https://www.adstxtvalidator.com/
I get this error

This file’s content type is text/html . The ads.txt spec requires text/plain; charset=utf-8 (setting the charset is optional but recommended)

Any help will be appreciated thank you

Sorry, you cannot do this. because of this security system:

If the provider has another option, such as DNS CNAME, you might get it to work.

Ok thank you for your help