An error message like "Index was outside the bounds of the array" is an indication of a bug in Skyline.
It is possible that there is also something wrong with your .csv file, such as maybe one row has fewer columns in it than all of the other rows, but, it's certainly a bug that Skyline is not giving you a helpful error message telling you which line it is choking on.
Error message boxes in Skyline all have a copy button in the lower left corner. The copy button will copy the entire text of the error message plus everything that you would see if you were to press the "More Info" button.
If you could send us the entire text that you get when you push that copy button, we could probably tell you exactly what sort of thing Skyline is choking on.
It might also be helpful if you could send us your .csv file as well as your Skyline document.
In Skyline you can use the menu item:
File > Share
to create a .zip file containing your Skyline document and supporting files including extracted chromatograms.
If that .zip file and/or your .csv file is less than 50MB you can attach them to this support request.
You can upload larger files here:
https://skyline.ms/files.url
-- Nick