I have an original stake in a wallet with the keys, but I've never managed to get the client working on my Mac or PC. Is there a way to access them without having to install the Client? Not sure what to do with the files downloaded from Github. As you can tell I don't really know what I'm doing, but would like to access the coins.
Try the lightwallet. Can't do much wrong there
http://bob.nem.ninja/lightwallet-standalone-1.7-cdn-nginx1.8.zip .
You can also try
http://bob.nem.ninja:7777 but it's recommended to run it locally for security reasons. bob is a node run by a dev though so you should be fine there.