@barillaro

make clean
make

they did the magic.

After that, I was able to continue up to Step $5.
There, I have an error when I try
pi@RAK831:~/RAK831_LoRaGateway-master/lora_gateway/libloragw $ sudo ./test_loragw_reg
./test_loragw_reg: error while loading shared libraries: libmpsse.so: cannot open shared object file: No such file or directory