issues when Installing material libraries

Hi, Im completely new and I apologise if this has been covered before, i did check on search but couldnt find a solution.
I have just downloaded KT on my Macbook pro and every time and try to install materials I get either of these messages depending on how i try to import them.
Does anyone have any ideas of why or how i can resolve the issue. I have tried renaming them, removing numeric data and reinstalling KT, all no no avail.
Thank you in advance
G
I have just downloaded KT on my Macbook pro and every time and try to install materials I get either of these messages depending on how i try to import them.
Does anyone have any ideas of why or how i can resolve the issue. I have tried renaming them, removing numeric data and reinstalling KT, all no no avail.
Thank you in advance
G