Differential Amplifier for ADC
Since you want to convert the output from an audio mixer, it will be at the line level, which is standardized to be an AC signal with peak values defined by the standard in use. The maximum voltage that you can expect is +-2.192 V, or 4.384 Vpp.
Your ADC takes signals in the range [-0.3 ÷ AVdd+0.3], so you'll need to both amplify your signal and traslate it from centered in 0 to centered in AVdd/2. You'll need to tune your amplifier/shifter (better to use pots) to cover as well as possible the range of the ADC without distorting (consider that amps usually distort before the saturation threshold).
If you look at the datasheet of the ADC, it suggests an input buffer that you can use to condition the signal from the XLR input:

Edited out:

If instead the output is single ended, you can also do it with a normal precision op-amp in level shifter configuration. You can as well use a rail-to-rail op-amp, or use a &quot;normal&quot; one with slightly larger voltage range. But using the same supply of the ADC may result handy. You'll need to tune your amplifier/shifter (better to use pots) to cover as well as possible the range of the ADC without distorting (consider that the op-amp usually distorts near the saturation threshold).
In this post you can find some ideas for level shifters, such as: