Wasn't sure where to put this, so figured I'd try here. I'm looking to plumb my next machine in. Is it a requirement to drill a hole and go straight down from the machine, or can you have some bends? Currently. I have a hole in the side of a cabinet for a waterline to the fridge for the ice maker. I was thinking I could expalnd that hole and run the water line and drain line through it, but I'd have to go slightly sideways from the machine and then down to the hole, and then back. Is that possible? Or do you have drill a hole under the machine and go straight down.

I would say that as long as the water is flowing downward at a good angle, you should be OK. We haven't had any drain problems since our machine was direct plumbed & drained over 5-years ago.

Here are 3-pics of our installation. In the counter shot, the hole coolest to the 20amp socket is for the drain, the other hole to the right is for the water supply.

Water supply line you can route as you need. Drain line needs to have a continus down slope.

You should check the water line requirement for the machine. Something like a refrigerator water line will probably be too small. Most plumbed in machines require a pressure regulator to step down your mains pressure and a 3/8 inch supply line. Adding a shutoff valve inline is also a good idea. An inline filter system is also a good option.

This is mine.
12mm silicon hose from the drip tray to an irrigation T piece.
18 Mm breather going up, 25mm drain going down, under the floor is a U bend.
Without the breather it would get overloaded.
The 5mm supply line easily keeps up with the pump, I am just careful when draining the steam boiler to do it in batches.
It is only turned on to drain generally.
Sorry cant get it to stand up.

My drain goes sideways about 10 inches before going down in the counter hole. It's on a descending angle and I haven't had any issues

As has been mentioned, the drain line requires a downward slope throughout its course, because its flow is dependent on gravity. Mine drops only about 1 1/2", running at only a slight angle backwards from the drip tray to the countertop hole (yeah, I have a hole drilled through the granite countertop). It has worked fine for more than a decade. The hole in my countertop also serves as a pass-through for my supply line and filter meter.

The supply line is pressure fed, so its course doesn't matter much. As long as it's not making some wild hairpin turn, or otherwise restricted, you should be fine. Whether or not you need a regulator depends on your city supply. Houston water pressure is just a tad under 4 bars, and has been consistently the whole time my machine has been plumbed, except for two instances when the pressure dropped considerably. One of those was a mains burst in my neighborhood several years ago, and the other was when we had the Polar Vortex last year freeze pretty much the entire state of Texas. So, I've never needed a regulator...and, lucky me, this is ideal for preinfusion of my preferred bean style, which is light to medium roast bean. That said, if you're planning on playing around with pre infusion pressures, you can certainly make use of a good regulator even if it's not "necessary".

Mine goes down behind the furniture, rests on the floor for about 1.5 meters, then up again about 20cm in the drain hole. No issues so far. I'm aware that there will always be some water left but that also acts as a "smell trap".

AFAIK La Marzocco recommends using a regulator anyways, and I think that's good practice. It will also protect you from unwanted "pressure profiling", in case the dishwasher maybe turns on when you're pulling a shot