@DrPTF ,
Each Unity version has a lot of changes for good. Unfortunately, these changes have some chance to not work properly on older versions.
Normally, if the jump between versions is not too high, the things that need to be fixed should be very little.
With a little bit more experience, I’m sure that you’ll be able to solve such issues by yourself, but as a beginner, you should try to avoid as many problems as you can in order to focus on learning the core.
Using the same version of Unity, than the one that was used to create the tutorial, is not mandatory but can make the things for you a little bit easier.
If you really want to avoid the installation of such version of Unity, what you can do also, is to ask your specific questions about the 3D Game Kit tutorial, in the official forum: 3D Game Kit Official Thread
You’ll have better chances to get support to those specific questions.
Good luck with it!