I would not get an STA. At least, I would try the rig first without one and get one later, if I decided I wanted one.
I had "regular" cam bands for 7 or 8 months of diving. I thought they were a pain in the butt every time I had to change tanks while out on a pitching boat. Especially with galvanized tanks, where the straps don't slide very easily. Then I tried some Highland Quick Release tank straps and did not like them at all. Then I got some ScubaPro-style Quick Release tank straps and LOVE them.
Dive Gear Express will ship anywhere.
They have the SP-style tank straps for USD$20 each here:
https://www.divegearexpress.com/tank-strap-quick-release-with-s-s-hinge-buckle
I have these exact straps now and I cannot imagine myself ever going back to the cam band style tank straps.
And, if you decide you really do want an STA, they have one for USD$25 here:
https://www.divegearexpress.com/dgx-premium-single-tank-adapter
I have never used an STA. I have never had any issue with my single tank rig where I thought having an STA would be nice. And the idea of moving the tank a little further away from my center of gravity does not appeal to me.
Oh, and lastly, if you're buying DIN regs, you might want to have a DIN-to-yoke adapter in your dive kit, for "just in case". And, conveniently, DGX has them for USD$20 here:
https://www.divegearexpress.com/dgx-din-to-yoke-spin-on-adapter
Sorry if I sound like a shill for DGX. I have no affiliation other than being a very satisfied customer. They have good products for good prices and GREAT customer service.