Basic question during installing the app that you could meet and also provide some solution to fix the installing issues. If these answer could not be, raise net thread on our discuss community:

My Android simulator not run with Expo ?

First make you you can open the Android simulator successful by using Genymotion

Could not connect to development server

First, make sure your have run "yarn install" or "npm install" to create the node_modules folder

Then, try the press the Restart button from Expo and Ctrl+R (Window) or Command+R (MacOS) to reload the project on simulator. We will able to see the Building Javascript at bottom of the simulator.