"In that day"? Didn't Adam die some 900 years later? So God is perfect in every way, except in giving dictation? Or, did Moses write it down wrong? No, that doesn't work either does it, because God's Word is perfect also, correct? So, even though it say on "that day" God really meant on a different day. So God speaks in general terms, not literal terms? No, that doesn't work, because if the Bible isn't literal, then what good is it? Fallible people would just come up with all sorts of weird interpretations. And, we all know that could never happen.
So the Bible has to be literal. Therefore, Adam died that day, but God must have resurrected him, and then cursed him and made him suffer for 900 years before letting him finally die... and go where? Was hell created yet? It must have been, because Adam was imperfect and, therefore, unable to enter heaven. Or, he's been in the grave all this time. His body turning to dust and his soul or spirit, whatever you believe is the eternal part of man, sitting there in the dirt, waiting for judgement day? But where is Adam's soul going to go? Did he ever repent? Who knows, but why would that matter because that would only be his "works". And the NT says that your works can't get you into heaven.
Or, maybe, just maybe, could it possibly be, that it's all myth? No, impossible. That would make too much sense. It has to be true, because who would make up stuff like this?