UnauthorizedAccessException from PowerShell when using Invoke-WebRequest

I know that the error is pretty much self-explenatory but yet I am not able to find solution. I write a PowerShell script to automate the set-up project for the dev machines. There are a set of programs that must be installed so what I want to do i first download the file and then install it. I am having problems with downloading file from the web to the local machine.

My logic is as follows. I have an .xml file where I configure all the stuff. For the downloads it looks like this:

<download source="https://github.com/msysgit/msysgit/releases/download/Git-1.9.5-preview20150319/Git-1.9.5-preview20150319.exe"
destination="C:\Temp" filename="Git-1.9.5-preview20150319.exe"/>

Then in my PowerShell script file I have this function:

function install-tools() {
Set-ExecutionPolicy RemoteSigned
$xmlFileInformation = $config.SelectNodes("/setup/downloads/download");
Foreach ($file in $xmlFileInformation)
{
$("Filename: " + $file.filename)
$("File source: " + $file.source)
$("File destionation: " + $file.destination)

    $("****************************************************************");
    $("*** Downlading "+ $file.filename);
    $("****************************************************************");
    Invoke-WebRequest $file.source -OutFile $file.destination

}

$("Task finished");
}

After executin I get the error from the title UnauthorizedAccessException from PowerShell when using Invoke-WebRequest. Two things that I can mention is that I have included Set-ExecutionPolicy RemoteSigned and also, I execute the script running PowerShell as administrator. I've tried different paths but it's the same everytime, I don't get permission to write anywhere. The only thing that I can't try is using another drive I have only one - C:\.

And one strange thing - my destination directory is C:\Temp but during one of my attempts I didn't have such a directory in C:\ so I ended up with file named Temp in my C:\ but this was the closest I get to getting a file.

I don't need to save those files in a particular place since it's very possible to delete the entire directory after successfull set-up so what I need is a way to let powershell save files somewhere in my C:\ drive. Since I'm not sure if this is related with administrating my system and setting the correct rights (I tried to lower the protection as much as I can) or I miss something in my PowerShell script?