The "packet" refers to "Packet 3 & 4". Each embassy handles it a bit differently. This us where instructions begin to deviate. I'll give our example ..
We were processed through US embassy in Bangkok. After NVC notified me (petitioner) that our case was bring forwarded to the embassy in Bangkok, I soon received and email from the embassy titled "K Visa Packet 3 & 4 instructions". The email informed us that we could schedule our interview, but to first follow instructions on the embassy website.
The website had the "packets", which were simply a PDF file with instructions for next steps...which documents to prepare, information about the required medical exam, etc. In fact, for us, there were no longer separate "Package/Packet 3 & 4', but rather a single "Packet 3, in PDF format".
I just checked KL embassy's website for the "packet" instructions, but couldn't find anything.