domain name problem with django app dployed with heroku

i'm trying to add adsense to my django web app but i can't activate it because of "no content website" error.

i'm using heroku to publish my webapp and i've seen that my website work with this way "mywebsite.herokuapp.com" but doesn't work with "https://ift.tt/3nCYUe4" and it's probably because of that i had this error.

when i'm trying to acces to "www.mywebapp.com" my browser show me a page with that error : inaccessible website , DNS_PROBE_POSSIBLE

in my settings.py file, the allowed_host line contains "mywebapp.com", "www.mywebapp.com"

did somebody can say to me how to fix that in heroku web app's settings eventually or directly in my project files.

thank you for helping me !