PLEASE FOR ASSISTANCE FOR NAVI PLUS

Hello everyone
Now I've retrofitted the navi Plus in my A8, so far so good.
The part also works very well on its own, except...
if I have set the map view and entered my location manually and then started, I am about 500m ahead of the navigator after about 5 km.
Does anyone know how to calibrate the part properly?
I have now entered a circumference of 1900 and a clock of "8. I'm still going crazy