It's part of your pre-trip inspection, to know you have the right equipment, including fire extinguisher, road reflectors, etc.
As a driver, you also have to know any state laws that require your special attention, not only chain laws, but lets say frost laws, bridge laws, etc.
The company should provide the chains for their rigs, but it is up to the driver to let them know, if they need to provide you the necessary chains.
Maybe the last driver took the chains that were on the rig to use on another rig, and the company is unaware of that.
It's part of the job, even as a slip seat driver, to know what you need to make the delivery.
You should not have to provide things like chains, load locks, emergency equipment, and if it's not on the rig, you must speak up.
If you are on the road, the company can still give you a com check to buy or replace what is needed.
One thing they can't require of you, is to drive when you feel it's too unsafe.
Chain up driving requires a driver experienced in chaining up, and driving with chains, and that's probably only 10% of OTR drivers.
You would know if yer one of them, eh.
Oregon is one of those lost communist states with fascist laws.
California and Washington are also communist waste land.
You will never know all the regulations required of you.