You need to hit the green button which looks like “3ABEPWNTb”. Then you will see an other play screen which offers the flags.
This was a game mistake on russian version. When i go to english version the map of level changed and in russian two.
The thing about submitting a level is that when it gives you a random seed, it gives you a random map as well. This is why you need flags, so you can navigate in real-time.