As stated in the first screenshot and in the mail you have received, you need to reach the rank Six Paths Sennin at least once to be able to receive the rank rewards for that season otherwise you will only be receiving the basic rewards which is the ninja student one.

Oh.... the grammatical syntax of the mail is quite misleading.Thanks for your help mr moderator.You can close this thread if you want, I got my answer

Hello i am also having this same issue but i do not understand how come other players which are lower power and level then me also never reached six path and still receive normal rewards ?

You have to reach Six Paths at least once before being able to obtain Seasonal Arena rewards based on your rank.