No you don't. All 4 loadouts can be used when you get weapons
The pay to win aspect of the game is mostly about adaptability. The more choices in your loadout the more adaptable you are in any given situation. People with money are more adaptable straight away.
Free players level up slower and so find it very gruelling trying to purchase weapons and upgrades. If I remember right, after reaching a certain level a free player will unlock an additional loadout slot (bring the number of loadouts to 2). Now if you want more loadouts you have to purchase them with real money.