Don't know about now, but some years ago for me, (with many years airline experience), it was a formal interview and a SIM ride. It was all very down to earth - if you were a normal, and nice person with your feet on the ground, and could competently hand fly and trim a 737 Classic, you would likely receive an offer. There was very little bull**** in WA and a good head office team.
Not to put anyone off, but freight Ops with WA was very much up to the two pilots - there is minimal support on the ground - (but a good Ops team on the phone). You need to be pro-active and basically organise most of the elements of the shift yourselves, including taxis to hotels etc. If you are coming from a passenger airline and are used to having a cabin crew, food, creature comforts and ground agents, it is a bit bare and basic, but you can learn your skill, and get into the LHS.
Leipzig airport freight operations* at night is an eye opener - a really big and professional operation.
*A DHL facility, but WA fly freight there.