There is currently not really such a thing as a Nutils adapter. Coupling Nutils is so simple that directly calling the preCICE Python API from the application scripts is the way to go.

The best way to learn how to couple a Nutils application script is to look at some examples (unless stated otherwise, all require Nutils 6):

To install a specific version of Nutils use, for example: pip3 install --user nutils==6.3.