File Import Failure getting error

Try switching to the Media Browser panel.  When you navigate to the SD card data that you copied to your hard drive, you should be able to view the video clips on it and import them to your Premiere Pro project from there.

Learn Premiere Pro > Import a range of media types > Browse, inspect, and import a variety of media types using the Media Browser in Adobe Premiere Pro

If that does not work, try switching to QuickTime Player to open and convert the movies.  You can also try Shutter Encoder (donationware). 

Also, under macOS, we can right-click the PRIVATE folder and choose "Show package content" to navigate into that data structure.  You should eventually get to a STREAM folder that contains the MTS files.  You can copy the MTS files out of there, but I would not move them.