The following instructions were tested on MacOS 10.10 (Yosemite); they are supposed to work as well for some earlier versions (10.7 and up).
Step 1. Download the profile, then double-click on it to start the import procedure.
Step 2. Click “Continue”, you'll be asked if you're sure to install the profile.
Step 3. Click “Continue” again, you'll be asked for ID data.
Step 4. In the “Username” field enter <your username>@h-its.org.
Step 5. Click “Install”. You'll be asked to type your local password in order to make configuration changes. Please note that this is the same password that you used to log on to the computer - it is not the password you use to access the e-mail!
Step 6. In the dialog which opens, enter your password - this time, the one you use to access the e-mail. You can choose (though not recommended) to save it by checking “Remember this information”. At this point, the authentication should succeed and access to the “eduroam” network should be granted.