How to perform OTA usinf DFOTA API in M65

hello guys,
I am working on Quectel M65 module. Can you please help me with these?

1] How to perform FOTA operation using .pack file available inside memory.(Withought using http/ftp)
2] “void Ql_DFOTA_WriteData(const unsigned char *buffer, u32 Length)”
buffer:
[In] Point to the start address of buffer.
I dont get what this buffer is used for?

Thank you.