I am new to CUT, how do I catch up?
Grind out Challenges. National Championship, Game Changers, Legends, etc... all give you decent free packs that contain BND cards to jump start your team.
If you're willing to spend money ($20 or so) buy the Game Changer Boosters and maybe the Rewind Boosters (though I'd wait until the new promo drops today to open those) as they give you a decent chance at good cards for a few bucks.
Otherwise, grind solo seasons on All American difficulty. Super easy and you get around 18k per season plus 2 field goal packs. No guarantee you'll hit anything out of those, but the cards are auctionable and while starting out, sell everything that goes for more than 2000 coins.
dude above gave great advice, only thing I'd say is if you hate solo season grinding (worst thing ever imo in terms of fun) you could run through the house rules, pretty solid rewards and quicker games.
I would grind against cpu (challenges and solo seasons) until u have about an 88 ovr bnd team and probably 200K coins. with those coins get either a top tier rb or qb depending on if u r more pass or run centric. Once u get to that stage begin to play house rules for free rewards. If u r up to it, try out h2h seasons and get to the all-conference division (no demotion possible), or cut champs. After that try to upgrade your dbs and then do whatever you want. Have fun and don’t rage too much.