I’m using the instructions that are available on the same page where the installer is on the onlyoffice.com website. The server has working internet as well. The problem is that the URL to the MySQL installer that is hardcoded in the installer no longer works as the file has been removed from the server. I can also add that the Enterprise version of the installer has the same issue.
It is the same problem that is described in this post (Thank you Google Translate)