https://help.infixsoft.com/wp-content/uploads/2019/08/RocketWeb_issue1-1024x494.png

After downloading I follow video and guidelines but get this error my app is not running.

It’s not RocketWeb problem it’s Android studio problem. Android studio take some cases which maybe corrupted in your pc. 

Because of its Android studio problem you are not the only one who fetch. *Please turn off instant run*. 
File > Settings > Build,Execution,Deployment > Instant Run> Un-check(Enable Instant Run to hot swap code)

Please read this for more information: https://stackoverflow.com/questions/42687607/application-installation-failed-in-android-studio