Choose GL Transmission Format (.gltf) to export all results in one gltf file, the results including autogenerated Meshes, Skeleton, and Texture.
Because .gltf is a very new format, not every 3D software officially supports it, you can use Don McCurdy's online website, glTF Viewer https://gltf-viewer.donmccurdy.com/ to check your exported result, make sure you drag the folder which including the .gltf file and .png texture file into the website.
Align selected nodes vertically with center anchor. Normally, the center anchor(a Triangle) is not show up, you can turn on the Part Mirror to make it visible, then turn Part Mirror off, the center anchor would not gone once showed.
Mark As
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Mark selected nodes as specified body location explicitly, such as Leg (Start), Leg (Joint), Leg (End), and Spine.
This will help the rigging step generating more reasonable result.
Usually, you will no need to use this, because the Rendered Model always show. But if you can not find the Rendered Model and you are sure the generation is done, then maybe it goes to some weird position, you can use this menu item to reset it's position.