So the internet and my brother and friends say that once you soloed greater rift 70, the first time you do, you get one. I never did, am i missing something?
Yes, but only in Season.
In non-season you still unlock Primals after a successfully cleared Solo GR70 within the time limit, but it doesn’t drop a confirmation Primal (there is a small chance a Primal could still drop, though)
I am seasonal character
There are two ways to tell if you have completed it.
Look in Achievements >Season> Greater Rifts and see if Primal Soul-O is there or if you reached 1200 Blood Shard cap.
If it is there, you might have accidentally salvaged the Primal. Check your mats to see if you have any Ashes.
The gift Primal is often a relatively worthless item and can easily be trashed without looking closer.