Smite has certain ranked requirements that you have to fulfill before you can get into them. It's different for each of the game modes. This is what you need.
If you're coming from LoL or Dota, the Ranks, MMR and Elo system in Smite might confuse you. But don't worry, it's actually pretty simple.
With the Fire Giant Update in Season 10, Smite's max Level cap was increased from 160 to 2000. As of the latest news, the highest level player is in the 400s.