How do you add more dino in sanctuary?

In my alliance I saw player has 8 slots full.why can’t I do it?

The notes say that players can add 4 creatures to any sanctuary at a time.
The Alliance link doesn’t show the player’s creatures. It shows what is in the Sanctuary. So the player may only have one creature there but there’s 7 other players that put creatures there.

However, you can place up to 4 of your own creatures at the same sanctuary if you want.