can you please check what's the value of the upload_max_filesize PHP variable?
if it's 2M, you must increase it at least to 4M...

Our website builder didn't see any upload variable so he thinks it means that we'll have to add our own. If so, then how would that be written in our configuration.php file?

hello!

that's a default variable in any PHP installation, which is found on your php.ini file
actually you can see its value if you go to joomla admin -> system information -> PHP. it will tell you where your php.ini file is located and what's the value of that variable.

This has been far too complicated for us up to this point and we realize this will continue to be. Could you please install it for us if possible?

yes no problem, if I have access to the files I can do it.
please, email me the details at joomlamusicsolutions@gmail.com