PS, here are the steps that I took:
1. I created a packet through on the dashboard with the plugin;
2. I uploaded to my “public_html” folder (either directly or with an FTP client, yielded the same result below);
3. I set up the database through the cpanel with my host, along with a prospective user & pw;
4. I ran duplicator as indicated with my url/installer.php
5. immediately got the warning mentioned above, in terms of the directory not being empty, and when I clicked my agreement with the terms
6. got the second warning