Thanks for providing the driver link ;
I've downloaded driver and extracted , and even after extracting the source folder i see in the driver directory there are driver files present as filename.dl_ which is an archived file format and driver manager does not understand this files and hence failed to import , This is a know behavior and we do not support importing of such driver files ; in future releases we are planning to support these kind of driver files.
You need to have the driver which are in complete extracted format i.e. All files referred in the INF file as dll, sys , exe should be present as mentioned.
If you did not find the driver in such format , then you can use expand command to change file to complete file name , i know this is a tedious thing to do.