Sorry you had an issue....but you can't assume a used pedal comes with an adapter. It's irrelevant if it had one originally. The ad either said it came with one, or it didn't. Period. That's just how used stuff works, anywhere...not just Reverb specific.
Working through a similar experience with Reverb. Bought a PRS SE Santana that the seller advertised as "Mint condition with a perfect setup!". The nut was trashed, the frets were rusty, and the pots were scratchy. I sent him photos and he said it was impossible - like I was trying to set him up. And this is after I waited an extra two weeks for USPS to lose and find the guitar without requesting a refund (which I could have within Reverb's T&Cs). Not a guy I would trust to process a refund. I replaced the nut and cleaned the pots, NBD... good lesson that buying gear is still "buyer beware"! BTW that LP looks freaking amazing!
"Buyer beware" wasn't put out there for nothing... Many used items are just the hardware, not the things to hook them up with...no battery compartment ? Wasn't made that way...