URL not found Error message instead of Admin Screen

I followed the instructions here: https://codex.www.ads-software.com/Giving_WordPress_Its_Own_Directory
So that I could control the look and feel of the template that was purchased for: https://montymarsh.com

In addition I am also working on a Mac and during the installation of WordPress it instructs for MAMP to be installed to use MySQL. So in my attempt to use the localhost:8888 as the root directory I received the URL not found Error Message as soon as I hit save changes and now I cannot access the admin page. So the site now looks like a skeleton and I don’t know how to access what’s needed to fix the problem.

That page did mention that this would happen and I would need to copy the index.php and the .htaccess file from the WordPress directory to the Root directory, but I can’t find the .htaccess file. In addition I can’t seem to connect my MAMP/Apache server to the FTP client I downloaded Cyberduck. I’m not sure of if I need an FTP client and since this is my first time working with a server (I’m used to this early part of the process being set up already), I’m having a few issues connecting the dots. Please someone help!! Or at least help me access the admin again.