I fount some samples for what I need to complete this one part. I need the unreal engine 4.15. Does anyone know when I can download it. or is there a way to update the BP classes to the 4.21.
in the unreal engine library tab, in the top left corner, there is a + button when you add an engine to launcher and you can select the engine version to install
Thx, I did find it. t only gives me 3 choices. and they are the newest ones. I just have to find something thing newer.
All UE4 versions are included in the dropdown, all the way back to 4.0
I click on the plus sign and it only gives me 3 choice. and then the plus sign goes gray and won’t let me select it.
Hello, I am also looking for version 4.15 and all I can find is the same instruction but my launcher only gives me the latest version? 
If you are still wondering how to do this: When you click the + in the top left, next to “Engine Versions”, below that, you will get a new Tab with Engine #XYZ. That Tab has a drop-down arrow in its upper right corner. That is where you can choose the version number you are looking for, and install it.