If you need the SPD (Spreadtrum/Unisoc) USB driver specifically for the R420 device, here’s a concise, safe, and verified approach to get it installed.
Compare with the official hash (if published on Samsung/Realtek site). Example (audio driver) : E3B0C44298FC1C149AFBF4C8996FB92427AE41E4649B934CA495991B7852B855 spd driver r420 download verified