Same. Thankfully, the post explains it as needing to drill open the PVC drain pipe under a sink where the washer drain pipe connects, inside a pre-formed attachment point. See "Solution 5" through "Solution 6".

If your washer is draining and working, there's no latent issue to worry about.

Most PVC under sink siffons have a preformed connection point where most people connect the dishwasher's hose.

The ones I encountered had a tapered pipe point for several diameter drains. You saw off to the matching diameter of your hose.

Often you would also put on a flowback protection valve so dirty water from e.g. draining a full sink would not get into to hose of your appliance.

The one mentioned at the very end: the drain pipe the washer's drain connected to had a PVC cover that needed to be drilled/punched out (since if a washer wasn't connected it'd be a hole in that drain!). If you're replacing another washer, it was probably already punched out.