Diagnosis
That's a dry or damaged drive chain. The ChainMax uses a metal chain on a metal rail, and without proper lubrication, it gets noisy and can wear out the sprocket.
How to Fix It
You need to lubricate the chain, rail, and trolley. 1) Unplug the opener. 2) Get a garage door opener lubricant (a white lithium grease spray or a dedicated chain lubricant works best). 3) Spray a light coating along the entire length of the chain, focusing on the links. Also, spray a bit on the rail where the trolley wheels run. 4) Manually run the opener through a cycle by pulling the release handle and moving the door to distribute the lube. Re-engage the opener and plug it back in. Run a test cycle.
If That Didn't Work
If it's still noisy and jerky, inspect the drive sprocket (the gear the chain wraps around at the motor end). If the teeth are worn down or hooked, the chain is skipping. That requires replacing the sprocket and likely the chain as a set.
Heads Up
Do NOT use WD-40 or similar penetrating oils as a lubricant. They attract dust and grit, making the problem worse in the long run. They're also a fire risk near the motor.