File > Export > Report ... Click Edit List... Click Import.
The term "Skyline library" is somewhat ambiguous. There is no CSV conversion for a Skyline spectral library (.blib file), but if you are trying create what tools like OpenSWATH, Spectronaut, PeakView consider a library, then this is just exporting the Skyline Targets list in a certain tabular format, which can be done, but you should consult the owners of those tools for how to do it, which maybe you have judging by the name of your .skyr file.
Hope this helps. Good luck with your research.