I think you are out of luck, I don;t think you can download it from anywhere else.

Microsoft Remote Desktop - MacOS Mac OSX Microsoft RDP 2.1.2 Mirror. Microsoft Remote Desktop V8 OSX Download Download OSX 10.7 Download v8.0.34. Powered by Create your own unique website with customizable templates. This article describes an update for the Remote Desktop Protocol (RDP) 8.1 in Windows 7 Service Pack 1 (SP1) and Windows Server 2008 R2 SP1. This update package provides the following improvements: Fixes connection reliability issues. Provides better error messages for connection failures.

Maybe also look into http://cord.sourceforge.net

Why don't you try downloading it on your computer and see if you can extract the file from the download? Right-click and show package content.

PS: Is that: https://www.microsoft.com/en-us/download/details.aspx?id=465 the right client?
I can't test it since I don't have a MAC at work.

or this one: https://www.microsoft.com/en-us/download/details.aspx?id=18140

The Windows Update in question is KB2592687 and enables Windows 7 SP1 virtual desktop to be WAN ready with Remote Desktop v8 and RemoteFX. After installing the update you may notice that you still receive the message 'A valid gateway address must be specified.' when specifying a remote desktop gateway port number.

How to fix error 'A valid gateway address must be specified.'

Win a mac for free. How to fix error 'A valid gateway address must be specified.'

This may be due to the fact that the update has a prerequisite update which is marked as optional and is probably not already installed on your Windows 7 desktop. The solution for this involves uninstalling update KB2592687 via Control Panel -> Programs -> Uninstall Program -> View Installed Updates. You should then download and install KB2574819 which adds support for DTLS in Windows 7. This protocol allows client and server applications to communicate in a way that is designed to prevent eavesdropping, tampering, or message forgery, and is required only if you intend to use Remote Desktop.

How to fix error 'A valid gateway address must be specified.'

Once installed you must install KB2592687 again, you must reboot for the changes tp take effect, after which you should note that your remote desktop client version number is now at version 8.

Microsoft Rdp V8 Pro

You can then open Remote Desktop settings and configure remote desktop gateway with a port number.