Brynn, Unless you bought it without their advise, the shop that sold you a Quad set up for learning should hold their head in shame for selling you that board...The quad set up is a beautiful set up but requires a real good standard to get the best out of it, that & great waves to get those powerful turns in that the quad fins love. They're all about 'drive' dude. In normal conditions & where most learners are, inshore slop, the fins will feel stubborn....Basically, buy a board you CAN stand up on & improve slowly..Unless you're a lightweight or grom, even a mini mal can feel too tippy when learning. Too many people buy them 'cause they fit in a car not because it's the right board to be on..Bad Call...Think your size & height, if you're tall/heavier built then a 9ft longboard will have the same or better stability for you as a lightweight on an 8ft mini mal.
Volume,volume , volume is the name of the game when learning...Better to progress quickly on a bigger board than floundering in the shore break on too small a board.This is why surf schools use high volume boards. Of course you can go shorter if you so desire once the basics are mastered.
Never be swayed by media hype about fins etc. You probably will never be the next Kelly Slater so progress slowly & have fun..Surfing is a lifetime of learning.
It takes a lot of guts but ask guys on the beach as well where you surf. Most are stoked you ask for advise...Do it when they're coming in though rather than going out !