Stress test on Dash app deployed to Heroku


#1

I deployed my Dash app in Heroku. I have the free account and I want to perform some stress tests. I want to use the loader io. In the first step, I have been asked to verify my target page. The process is described as:
1)Place this verification token in a file: loaderio-6aaab********
Or download the file you need. (in case that you press the download button, you will get a .txt file with the token)

2)Upload the file to your server so it is accessible at one of the following URLs:

http://@@@.herokuapp.com/loaderio-6aaab********/
http://@@@.herokuapp.com/loaderio-6aaab********.html
http://@@@.herokuapp.com/loaderio-6aaab********.txt

But I have no clue what to do from this point. Any suggestions anyone?