As the message suggests, the error there is because `Invoke-WebRequest` cannot parse the `$url` variable that's being passed to it as a parameter. The message is saying that `$url` includes `System.Collections.Hashtable.Sitecore.InstanceName` - which suggests to me that there's something wrong with the variable replacement when the `$siteName` variable is being set up. 

`$siteName` should just be a string from your `psd1` file, rather than a collection.

Your question doesn't include the data from your `psd1` data file, but the first thing I'd check is that there's not a problem with that which is causing the value of `Node.Sitecore.InstanceName` to be something other than string.

Just to avoid any possible confusion - I did put some annotation into the [example data I gave in my answer to your previous question][1]:

[![Example with annotation highlighted][3]][3]

The bit highlighted in red there was just annotation - that should not be in the real file...


  [1]: http://sitecore.stackexchange.com/questions/4982/how-to-install-zip-file-package-from-installation-wizard-using-powershell-dsc
  [2]: https://i.sstatic.net/dC69s.png
  [3]: https://i.sstatic.net/YJPhe.png