When ordering licenses, you will be asked for the organisation unit name of your CRM system. This information is mandatory in order to create a license. Below, you can find a short description about how to get the necessary information for CRM 4.0 / CRM 2011.
Check the log textbox if the following statement is present (might be accomodated by a 401 exception).
Receiving a service unavailable response on a website usually indicates, that the application pool of the site is not running.
To solve this issue, open your InternetInformation Management and verify all required app pools are started.
Before you can upgrade your CRM 4 to 2011, you will need to uninstall all 3rd party addons and check that all buttons have been deleted. After the migration you can then install the latest version of each addon. Should you have not done this, then it will be more complicated to get rid of the buttons and icons before you can install the CRM 2011 addons.
This article contains a detailed guide on how to find out the version number for each mscrm-addons product in CRM 4.0.
The problem occurs because MS CRM is using an HttpModule for multitenancy scenarios. This http module is called with an anonymous user account. This is why it fails when trying to request, i.e. the metadata webservice.