Hi,
As I am a new UE4 subscriber, I have the 4.7 release.
However when I try downloading an Engine Features Samples like “Matinee”, it says:
“No compatible engine currently installed.
You will not be able to use Matinee until a compatible version of Unreal Engine is installed.
Are you sure you want to download Matinee now?”
Actually I can’t install any Engine Feature Samples, because I am using the latest UE release (at this time).
Should I keep updating UE if it takes me away some useful samples for self-learning ?
Thank you for your recommendations.
I wouldn’t use 4.7 until it has an official release. Unless there’s a feature in it that you absolutely need right now, there’s no reason to move to a new version, especially preview versions that are going to be more buggy.
You should keep several engine version around, especially if you are working on a project 
as of writing 4.7 is still in preview so it is recommended to have a 4.6 as well. 4.6 should be compatible with all the latest samples!
If you are working on a project and want to upgrade your engine version (perhaps to use new features) then make sure to create a copy of the project (the launcher should prompt for this when attempting to open the project with a newer engine version) in order to make sure that you don’t break anything vital in the project, as projects may need to be (automatically) converted to newer engine versions.
You don’t have to keep old versions installed by the way, you can uninstall them and at any point if you want to go back you can add any old versions back in.