Cabal Online won't start on Windows 11 — XIGNCODE3 error 0xE019100B, no idea what's causing it

Just installed Cabal Online off Steam (app 253490) on my Windows 11 PC. Launcher patches fine, but the moment I click Start the game closes and I get this:

XIGNCODE3
Error Code: 0xE019100B

That's it, no other message. Steam shows Cabal "running" for like 2 seconds then it's back to Play. I swear I'm not using any hacks or macros lol, it's a 20 year old game, I just wanna log in.

Stuff I already tried:

• Added the Cabal folder to Windows Defender exclusions

• Ran it as admin

• Reinstalled the whole thing + verified files in Steam

• Rebooted

Still the same 0xE019100B every single time. I've got Discord and GeForce Experience running in the background, not sure if that matters. My rig is a Ryzen 5 / RTX 3060, Win 11 fully updated, only Defender for antivirus.

Anyone know what actually triggers this error and how to get past it? Do I need to kill something in the background or is it a leftover anti-cheat driver thing? Kinda lost here.