It sounds like your computer is having trouble contacting the server where the ER files are stored.
Enhanced Resources require some additional data files to be useful and those are the files mentioned in the dialog. These are normally downloaded at the same time the first ER is downloaded.
I did check and the server is fine, I could get a list of all the Enhanced Resources. Try again and if you still have problems, send a problem report from Paratext that will give support more information about what is happening.
