The Permissions category is where you set who can edit your island from Fortnite Creative. This can be useful if you're creating an island and want other creators to join in and help.
There is one setting available for Permissions, and only two options.
When set to Private (the default option), only you (the owner of the island) has permission to alter the island.
When set to Public, anyone who enters through your personal rift is able to edit your island.
Even when you set the island to Public, only you can change the island name as described under Overview and Tools Settings.
The Permissions category does not have a Restore Defaults button like most of the Island Settings categories.
Sharing Your Island in Create Mode
Once you've changed your island permission to Public, friends can join you on your island and help you edit it.
From the lobby, invite another player to join your party by hovering over the player nameplate then clicking Invite to Party.
Once a player joins your party, you can both click Play to ready up.
Make sure the other player is on your hub, then walk through your personal golden rift. The other player can now also go through your rift and join you on your island, where you can both make changes to the island.