Error: "Channel not in Stasis application" when adding channel to a bridge

Question

I'm working with Asterisk ARI. When I create channels via ARI, I specify application name and I can add those channels to a bridge with no problem. But when I use other client (like Zoiper) to make calls, and try to add those channels to a bridge, I get an error "Channel not in Stasis application". I am not sure what is Stasis, I followed this article and put the following in extensions conf file, but it still doesn't work:

same => n,Stasis(myApp)
same => n,Hangup()

So, what is a stasis app and how can I be able to bridge channels which are created outside of ARI?