Zeplin exports assets which are images automatically generated from layers in Adobe XD that are marked for export. To mark a layer for export in Adobe XD, select the layer open the Layers panel, hover over the layer, and click the mark for export icon.
You can also use the “Mark for export” option at the right bottom of the screen.
You don’t even need to think about which sizes you should export the layers at, Zeplin will grab all the necessary images with different scales and formats automatically, tailored to the platform you’re designing for—Web, iOS, Android or macOS. Simply clicking the layer inside Zeplin will list all these assets to developers.