Newbie on assault squad

[goodyne34]

i'd appreciate some help from you guys,i bought assault squad from gamestop and i had to download it online, now my question is i keep hearing about all these maps, downloadable content and patches etc... my question is what are these patches and how do you play those maps, and the dlc on my game says it downloads from steam, heres my problem i bought and play my assault squad game thru the gamestop app on my desktop, am id like to download those map packs but will they work even though there from steam and i play the game thru gamestop, and if not can i use my redemption code from gamestop to download the game thru steam? as u can see im clueless lol and now im bored with the original multiplayer maps that came with the game and i want to play some of these others i keep hearing about!!!! HELP IS GREATLY APPRECIATED!!!! Thank You in advance for any help comments, and replies i might recieve from you guys, thanks