The right wrist of Athan and Tiana, where the " 1 " number appeared, had a border around it. This border was 16% filled up, and once 100% of it is filled up, They will be transported to the 2nd level battlefield.
Tiana didn't enter the town, but her wrists also displayed the numbers after she directly appeared on the battlefield with Athan when they first entered the battlefield.
To collect the rewards of the metallic beasts they killed, They simply have to tap on their right wrist where the level of the battlefield was printed, and the rewards will appear inside their Genesis Realm. This is so that other people don't try to steal it on the battlefield.
The Roumbra Blood war was ultimately a dimensional pocket world with five layers designed to train people and make them more powerful at a faster speed. While it also has plenty of bloodshed and ruthlessness, it also rewards those who survive.