Hello @Anonymous and welcome to the /e/ forum.
Two images shows RMM STATE : Prenornal, one shows KG STATE : Checking.
Any phone showing Prenormal will not accept a Custom ROM; as in
Only official released binaries are allowed to be flashed(RECOVERY)
We have to find the reason for this ! (From the time of your post, perhaps you are in the USA, and this is an imported device?)
Please read for suggestions of the cause in the later sections of this article: Know your hardware - Samsung (It is a long post, but please check for the key words I used in the Contents section.)