Thunderbolt 3 to 2 adapter

Apologies if this has been covered previously.
I thought I was doing the right thing by buying a Thunderbolt 3 to 2 adapter to connect a 2013 IMac to a new G-raid with Thunderbolt 3. I was surprised having spent £49 that it didn’t have a male connecter that went directly into the Thunderbolt 2 port on the IMac. Do I have to buy a male to male cable in addition to make it work? Should I have bought a dock instead?

Yes you would have to have a standard TB2 cable in order to use that adapter in that way.