Google adwords is very tricky thing. I had also faced similar issues when I wanted to use Google Adwords. Please confirm that you have already entered in any case one tag and also published the version of a container in your Google Tag Manager you must see the green box at the top right of your interface which should confirm that it is a Live Version.
I did lot of research on it but coming up with nothing but had only suggestions to turn off the AdBlock. When I looked at my Inspector/DevTools at my Network requests and then I realized that the request to my
gtm.js?id=GTM-XXXXXXXX script was showing the 404 error.
So after the publishing the above error simply went away and now my tag is working properly.
I hope the above solution will help you in fixing your issue and help you in publishing many more articles.