To import a 3D package in Eagle:
Download the 3D .STP model.
Make sure that you're logging into the Eagle panel control. If you aren't you can go to File > Sign In.
Open the library that you want to add the 3D model and go to Library > Create managed library as pictures shows. It will display a window and click on Create.
4. The previous Step will create a 3D package file on panel, please right-click on it and choose View on Web. This action will redirect you to library.io.
5. On this app, please upload your model clicking on Upload, browse the .STP model that you downloaded previously.
6. Compare your 2D model and set up the position of 3D model using the Package Inspector as the picture shows. Make sure that coordinates of both models match.
7. After set up, click on Export and select the LBR option. This will download a new library with the correct 3D linkage.
8. Go into the Library Manager > Available Tab, then click on the update Icon that appears on the 3D package. You should be able to see the 3D package on Device.