Cross compile on RAK7249

Hello there

Issue:
I am trying to cross compile C code in order to run it on the RAK7249 Gateway. I only found one forum thread (Compiling lora_gateway for RAK7249) which mentions compiling for the rak7249 gateway. However the provided SDK link does not work.

How can I cross compile my C code in order to run it on the Gateway? Could you perhaps provide me the build tools?

Setup:
My Setup is the RAK7249, running on WisGateOS 1.3.6_RAK

Thanks and best Regards!