I'm completely new to Chirpstack, never used this before and, quite frankly, the documentation is not very newcomer-friendly. I did manage to set up an Arduino-device, I can see it connecting to my Chirpstack-instance and I can see a message posted to topic application/6f121dc1-7e56-4713-a288-a5bd17bd5d81/device/09fd73a08f757e95/event/up on the MQTT-server, but....I have no idea how to get the data sent by the device!
I used the ttn-otaa.ino sketch as suggested by https://www.chirpstack.io/docs/chirpstack/use/devices.html#generic-arduino-lmic-based-devices and it's supposed to just send a "Hello, world!" -- it all seems to work just fine, but I can't find any explanation on why I cannot see the "Hello, world!" under any MQTT-topic. The linked page doesn't explain how one is supposed to set up profiles or devices, so I can only assume that I haven't set everything up correctly.