Day 2 is a short and simple trade. We're giving the meth to these Gangsters who will in turn give us dirt on the Mendozas. Grab a meth bag and walk up to their truck peacefully.
Normally you would throw the bags into the back of the truck and they would give you the Intel peacefully, but sometimes the cops bust the operation or the gangsters will backstab you. If you go loud, you need to search the buildings for safes and find the Intel before they burn it.
Open up all the safes until you find the one with the Intel. If you didn't get busted or backstabbed, the Gangsters would have shown you the correct safe and opened it for you. If you brought and traded extra bags of meth, there will be big piles of money in the room with the correct safe. (If you got busted, you can find the money to tell which safe is the correct one).
Once you have the Intel and any extra cash you might have earned, take it down to the van and get out.