PoE in on hEX PoE is passive so while it’s possible to power it by RB5009 which is active PoE you will most likely need to force PoE on on the desired port on the RB5009.
Reason is that active PoE uses negotiation with client that requests PoE to be turned on. And passive PoE just sends and receives power.
But be careful and remember that you forced PoE on… Some devices might not like 48-52V on their port. (Talking about the future and if you ever want to plug something else instead of the hEX PoE)
If you power hEX PoE with separate power adaptor then you will have active PoE on it, as stated on product page.