The instructions for the game are a bit sporadic so since I’ve finished it I’ll give you a quick breakdown without ruining the fun.
First you can talk to motel “clerk” or head straight to the PD, either way you’ll need a guzzle juice to bribe the detective. (A guzzle juice vending machine is in the PD if you don’t already have one but it costs 20 coins) once bribed he’ll give you the key to school.
-the school is across from the PD
Next go to the school and complete the battle to get the bank/farm key and go to that area to get the dam key.
-the bank can be found by looking for the high beams in the sky-
-the farm is located at the top of a road you can see it curve upwards from the gas station, and only small zombies will spawn on that road-
Now go to the dam and complete the battle to get batteries for the radio station.
-radio station can be located by looked for the elevator up the mountain-
Power up the lift and go up and grab the signal beacon and call for a supply drop, *the lab key will only spawn in one of a summoned supply drop*
Finally head to lab which is located under the waterfall and not on top of the mountain with its lettering.

Afterwards you defeat the lab a few times to get cube monster parts and then you can open the ultimate loot which includes a sword however in my personal opinion the scythe is better since it heals you.