As long as you have completed the Fortnite Tutorial, you can actually share Building permission with your other Party Members. By doing so, they will then be able to set traps, build, and harvest from your Storm Shield Base. Only the owner of the Storm Shield Base can give permission to other people to help build their Homebase, and anyone an owner would like to give this permission to must be apart of their party at the time they are adding them to the Permission List.
In order to give permission to other Party members, you must first access your Storm Shield Computer. To reach it, going into your Map and head to your Homebase Storm Shield. Once you are there, head inside your base to find the Storm Shield Computer. Once you have access to the computer, select the Permissions Tab at the top of the screen. This should lead you to a list of all of your Party Members under the Permissions List. From there, all you must do is select the names of the people you would like to give permission to. You will know it worked when you see a white check mark next to the party member's name. (You can do this same process to remove permission as well, taking away the white check mark if you do.)