Update LR to 6.3. You are running the very first release of LR 6
This error message means you are trying to copy the photos to a folder on your hard disk that does not have WRITE permission.
In order to fix this, you can either pick a different folder where you do have WRITE permission, or change the permission on the Destination directory (as specified in the Lightroom Import dialog box) to WRITE permission.
Could you please update Lightroom to Lightroom 6.3 and check if it helps.
Do you have video files as well in the camera card?
Please also try to copy the images first to your computer and then try to import them in Lightroom.
The D5300 was supported in Lightroom 5.3. Updating to Lightroom 6.3 won't fix the underlying problem (although it's probably a good thing to do for other reasons)