"Estoy registrándome dentro" (I'm signing myself up) it's totally fine. The problem lies on that the phrase looks like you are signing up first, and not logging

"Estoy registrándome dentro" (I'm signing myself up) it's totally fine. The problem lies on that the phrase looks like you are signing up first, and not logging in to a previous account. In Spanish you would just say 'enter in your account'.