civiCRM is on Ubuntu Machine! This is a Linux and does not have Remote Desktop enabled by default.
What you have added is an RDP endpoint (standard) for a Windows Server machine. It will not work with Linux images. With any linux images.
If you want to login remotely, your only chance is the SSH via port 22. Once logged-in on the console, you may install some X-Window and enable remoting on it. You will, however most probably need a VNC client for it and not the standard windows Remote Desktop Client.
You also most probably don't need a Remote Desktop at all. CiviCRM is a web-based open source CRM solution. Being web based, means that you have to access it over WEB.
Add a new endpoint - public port 80 and private port 80 for your VM. Then navigate to it with the browser! And you shall see the welcome screen of CiviCRM.