There are several ways to mount a two point sling onto shotguns. I am not familiar enough with the platform to know the pros and cons of each and would like to learn from our SMEs. On a carbine, I tend to run my two point slings with the front point close to the front site and the rear point on the buttstock on the "outside" (I am right handed so the outside of the buttstock is the right side). I tried this method with my Mossberg 590 with Magpul stock and it causes the gun to spin when it's slung. It doesn't seem to like the rear point being mounted on the "outside."
The options that I am aware of are:
Front Sling Mounting Point:
Magazine tube end cap thread in nipple-thing that lets you put the old style C-clip type (proper name?) sling point in it. This seems to be less sturdy than modern QD push button options. This option does seem to let you mount the sling as far forward as possible because this is the most forward point of the gun. It also lets you adjust whether you want to sling to be on the left side of the gun or on the "bottom" of the gun. To run it on the bottom of the gun, you'd need an equivalent sling mounting point on the bottom of the buttstock which my Magpul stock does not have, although could be drilled for.
Magazine tube adapter that is a little plate that goes between the end cap of the magazine tube and the barrel "lug" (proper name?) that keeps the magazine tube and barrel together. These come in both QD push button and fixed 1" webbing (loop the sling through) options. These are pretty close to the end of the gun but not as forward as the mag tube end cap. And you're limited to running these with the sling parallel to the gun, you can't run the sling under the gun as you could with the mag tube end cap. This seems more secure and sturdy than the mag tube end cap because less moving parts and things that might get unthreaded.
Mag tube/barrel clamps are an option for longer shotguns where you have a little "8" clamp that goes around both barrel and mag tube and puts the sling mount on the side. This is pretty similar to the magazine tube adapter option but won't work for short barrel shotguns because it has to be further ahead of the pump and there's no extra dead space on a SBS.
Rear Sling Mounting Point:
The magpul stock offers fixed sling and QD push button mounting points on both the left and right sides. I've tried the right QD sling mount point (outside for me as a right hander) and it caused the shotgun to roll inboard when slung. Could be my technique is bad. It seems like if you want to mount on the outside of the stock, you are limited to QD because using the fixed loop option might not allow the sling to flex and flow over the top of the gun properly.
There is not a bottom sling mounting point, although it might be possible to thread one in should someone want to run the sling under the gun (using the mag tube sling mount angled downward) rather than run the sling along the side.
Sling Hardware Types:
I'm not sure if I need or want QD push button functionality. It seems like an extra potential failure point. Possibly good for waterborne operations so you can escape from the slung gun if needed. I am a civilian that doesn't do waterborne operations so that wouldn't apply to me, but might apply to some. The QD does seem like it gives a bit of angled flex letting the sling move a bit more rather than be locked in place. Not sure if this is good or bad.
Misc Considerations:
I don't want the sling to run horizontal parallel along the left (inside for me as a rightie) part of the receiver and be too tight because it might interfere with me using the pump.
I'd like to be able to switch shoulders if necessary. Jeff Gonzalez is where I learned the carbine sling layout I use (with the rear point being on the outside of the buttstock) because if you're running the carbine with it slung around your chest or neck, you won't choke yourself if you switch shoulders if the sling is on the outside. I don't know if I would ever shoot the shotgun with it slung around my body for this to be a consideration. As a civilian, I probably won't, but I'd like to learn best practices.