RAK7371 unable to connect to TTN

Hello everyone, I hope everyone is well.

Newbie here…

We just recently purchased a RAK7371 developer base. It is my 1st time to use a RAK component, so don’t have any idea aside from the ones I got from the Quick Start of the component which can be accessed in this link RAK7371 Quick Start. I followed everything there from setting up to connecting to TTN. My set up is I connected the RAK7371 to my laptop that is running on Ubuntu OS. I’ve been trying to make it work but up until now I wasn’t still able to connect it to TTN.

Any help for this matter will be greatly appreciated. Thank you.