### Why does Sage Math crash instantly? / Running .sage files?

Hello.
First of all, I need to Mention that I am completely new to Sage Math and I have no idea what causes my problem(s), like seriousely, no idea.
When I start SageMath, it instantly crashes, I don't even touch anything. I'm running Windows 10 and I downloaded the binaries, a virtual box and this sage-8.6.tar.gz file. I am sure that I must be missing something but I don't know what.
Yesterday, I managed to get Sage to work, so in the terminal i could write simple commands like
sage:4+3
and later, I reinstalled python. Now it does not work anymore. My original aim was it to have sagetex in Latex, but for some reason running the .sage file which is created with every document using sagetex doesn't do anything and sage does not compile my document. And yes, I did follow the instructions how to make sagetex known to tex.
I have no idea how to continue, so many problems and i'm desperately trying to get things to work. (Feel like I downloaded half the Internet...)