If I die in a GR70 but I complete it within the time limit; am I still supposed to get a primal? Or do I have to complete a GR70 within the time limit and not die?
The only guaranteed primal is when you successfully complete your first GR70 (or higher) solo on a seasonal hero, i.e. you kill the guardian before the timer runs out. This happens regardless of whether your hero dies during the GR or not.
From the wording of your query, it sounds like you may think you get a primal every time you do a GR70 or higher, which isn’t the case.