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. 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 the app online.
5. On this app, please upload your model clicking on Upload Step, 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 Package/LBR option. It will create a new version of the library, select YES in warning log an automatically will update the library, also app will download another version, you can omit this one.
8. Click on update Icon that appear on 3D package and now the steps are complete. You should see the 3D package on Device.