Apple Pay verification issue

[Brahms234]

I run clarinetinstitute.com.  My shopping cart is handled by Ecwid.  I want to accept Apple Pay. To do so we are supposed to upload a verification file to a directory on the web server called .well-known. I don't see a way to get access to the file system. Is there a way to do this? 

In other words, Apple's instructions for verification includes downloading a particular text file and then:

Upload the verification file to your website‍
Host the verification file on your website in the following location:

https://clarinetinstitute.com/.well-known/apple-developer-merchantid-domain-association 

I can't figure out how to do this.  Please help.