Following the install explanations, we can't pass the "bundle install" step :

Fetching gem metadata from http://rubygems.org/...........
Fetching version metadata from http://rubygems.org/..
Fetching dependency metadata from http://rubygems.org/.
Fetching git://github.com/gregbell/active_admin.git
fatal: unable to connect to github.com:
github.com[0: 192.30.253.113]: errno=Connexion terminée par expiration du délai d'attente
github.com[1: 192.30.253.112]: errno=Connexion terminée par expiration du délai d'attente

We can't fetch "git://github.com/gregbell/active_admin.git" as it seems that this repository don't exist anymore ?

We have tried Ubuntu 14.04 LTS and Ubuntu 16.04 LTS : same problem.

We absolutely need an upgrade of Thingspeak and also the last install explanation is for very old systems now !

Thanks for your work...