Zeplin automatically exports assets marked for export in Adobe XD. When a layer is marked for export, you don’t need to worry about setting up export formats or sizes: Zeplin will automatically generate the assets with different scales and formats, tailored to the platform you’re designing for—Web, iOS, Android or macOS.
When you add an image to your artboard, Adobe XD marks it as exportable by default. To mark a layer for export manually, you can select the layer to open the Layers panel, hover over the layer, and click the export icon.
You can also check the “Mark for export” option at the right bottom of the screen.
After you’ve exported your artboard into Zeplin, simply click on a layer on the screen or go to the assets tab on the right panel to see a list of all the assets to developers.