How to run rocketchat mobile app locally for development?

I am not able to run rocket chat mobile app locally on a emulator.
I am getting the following error.

Can anyone help me solve this problem? @Menma

I found this place a while back and have tinkered around with selfhosted apps just for my local network. I really want to setup a Rocket Chat server on a dedi server that I already have but I always become concerned about security when hosting something publicly.

What are some of the steps you guys use to secure your snaptube vidmate server and your installs?