How to attach non-georeferenced images to a layer

Any layer that you either create by drawing, or upload can have images attached to it that aren't georeferenced.

If you don't have a layer, you can create one by using the drawing tool:

After you've created a point, line, or polygon, click on the item on the map. This will open the info panel menu on the right. If you expand the media submenu, you can click on the + Icon to add an image

Once you're done, click on the save button, and the image will now be attached to the layer that you selected.