The game wont load every single player, it will load players from the countries/leagues you select to play with and other medium/high reputation players form around the world
e.g. if you only had English prem loaded you wont be able to Manage India due to small amount of players playing ouside India and most with low world reputation... Whereas if you had Indian league loaded you would be able to manage India because hundreds of low reputation Indian players will be loaded because you chose to have Indian league loaded