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Copy the ‘aerialsphere-viewer’ folder and paste it into the following location: ArcGISExperienceBuilder\client\your-extensions\widgets
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Open the command prompt or terminal window and ‘cd’ to the directory where Experience Builder - Developer Edition was unzipped and proceed to the client folder
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Type npm ci and hit enter. This action may take a few minutes to complete
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Once each of those actions is completed, launch ArcGIS Experience Builder - Developer Edition