Official download from Joymax:
SilkroadOnlineGlobal_Official_v1_546.exe MD5: 28e99d9d3888063da6d5716acfd1c3f1 SHA1: 53d1407ea932b624d4986529998003f9108ddf91 SHA256: 0dab52133850d95969cb795c350794a5625ae487367bce3db5d6acdc98691078
There are two ways to sign up now. The new way is a JCP account which will use your email address to login to the game. Either option will work.
Be sure to accept the Silkroad game agreement and the in game GDPR notice.