idk where you're from or anything so I'm not sure what is available to you. But it's just a game that you like so just find a rec league or local pickup and play the game. Soccer/football is never going to be your job, so don't treat it like this obscure thing that you need all kinds of prerequisites for. Just get some cheap cleats/boots, a cheap ball, and find some grass. You should try to get the sense of what it's like to play as an adult and take it from there. Listen to more experienced teammates, 90% of strangers in pickups or rec leagues will be willing to give you advice and are usually nice. Trying to play full games gives you a sense of where you are in terms of fitness and you can go from there. But just play the game.