To obtain skins through the Steam trading system, your account must meet several requirements.
Make sure your account has:
1 Steam Guard enabled
2 Public profile and inventory
"Only for globals" is like an attempt to make an ordinary case into something exclusive and attractive only for elite players. It's like trying to sell a regular car for the price of a sports car by adding a few plastic details and a loud exhaust sound. "Only for globals" is like a reward for achieving the highest rank in the game.