Fairly sure this setup is quite competitive even among the more meta setups.

Race drivers always seek for the duality of physics: He/she wants traction. And Rotation. A good front end and a good rear. The truth is: It's all always there, but what the driver is unhappy with is laptime and corner speed. Always. The Audi has one of the best front ends you can find and it has good electronics, too. But with the big V10 in the back, there's a decent amount of weight that is trying to make your life harder. It provides good traction in quali and allows to slide the rear just about as much as you want. But in the race it will work the rear tires quite a bit and controlling temperature there becomes crucial.

Here on Zandvoort additionally we have the issue with the deep trailing and especially the fast right in the middle sector, which compromises the setup a lot everywhere else around the track. You need the car to rotate in high speed, but that will make it pitch sensitive into that corner. 

Electronics:
TC1 on 2 or 3 for Q and 3 or 4 for the Race feels best for me as the car allows you to actually work with the rear on throttle (The sequence seems to be 1, 2, 4, 5, 3, 6 ... and is mostly down to how much oversteer the TC will tolerate). I would keep TC2 low or off for Q but on 1 for the race.
ABS on 3-5 seems predictable

Adjustments (you dont actually need any imo)

• The spring steps are rather large
• stiffen front spring if braking into the corners is an issue or the car is generally too oversteery for you, yet its almost maxed out, so rather reduce rear ride height, or even lift the front. Another option could be to reduce front bump stop range (try 5)
• reducing negative toe or going positive on the rear can help this further, but the speed certainly is fastest with negative toe.
• move BB forward if too loose into the corners
• a softer rear spring will generally make the car more understeery in all scenarios, als make the rear anti roll bar softer
• adjust rear ride height for over/understeer by 1mm steps. Also consider raising the front as the downforce loss is minimal, which allows for subtle balance adjustments
• Raise the entire car a bit if you want more tolerance over kerbs, the car barely loses downforce with higher ride heights - however the weight travel will be more pronounced
• For lower rear tire temp you will have to shift the balance further. Lower rear ride height, higher front, stiffer front spring, etc. 

Driving

• the banking poses a challenge for the car. You need to trail a lot into the long 180° corners in the first sector. It becomes a bit better in the middle sector, but there isn't too much grip (we're at the beach!) and the car just waits to break lose - so be careful on the brake pedal
• Onto the throttle don't just floor it in the slower corners, give the car some time (say, half a second) and it will thank you
• aim for late apex in hairpins, try to trail deep, immediate but progressive throttle, little to no coasting in tight corners, aggressive throttle in longer corners. early power is very crucial to work the diff and unload the front.
• do not clip any of the inside apexes in the first sector, and only in the right kink you can use it quite a bit. Also in the 2nd to last corner the kerb is helping, but everywhere else its highly likely it will upset the car more than needed.

LFM:
Just reduce fuel load to 45/49L. Balance should become even more neutral. Adjust rear ride height +-1mm to your liking. Most likely up by 1mm for medium fuel loads. Also worth experimenting with one click of spring on front or rear to get more over/understeer in general.