I can't add an addon domain

I tried to create account using my domain skwad.ml and it didn’t register so I create an rf.gd subdomain account and try to add skwad.ml domain as addon domain and says “skwad.ml is already assigned and in use.4” I tried also to access skwad.ml domain and I saw it becomes free web hosting service website. Why it becomes like that? Please make skwad.ml domain available for addon domain because its my domain.

Did you sign up at MyOwnFreeHost.net by any chance? If so, you need to remove your domain from your account there first before you can use it here.