I'm pretty sure you can't go to the spawn island as this is of course where everyone spawns, hence the name "Spawn island". I believe it is the "spawn island" because, with all Altis Life frameworks such as 4.4 there is about 100 NPC's walking around the island, they have no goal or mission and they simply wander around. When someone spawns in game, they take over one of these NPC's that is wandering around and plays as the NPC, with their previous gear of course. If you were to go there, you could kill the NPC's and it could potentially fuck up the server until a restart occurs. (I'm not sure if all this is correct, but I'm pretty sure this is why you can't go there)