Just to make sure before answering your question. Are you trying to upload renders for your model? or for another user?
The rendering tab on your attached image is for rendering made for models that are made by other users. If you wish to verify look at my profile and go to rendering tab and you will see several renders I've made for other users.
Thank you very much patrick! It did answer my question. I understand the rendering clearly.
Thank you again.
Sorry for the late response you can upload renders on your model during or after you upload it on grabcad. Go to projects and click on your uploaded model and click on EDIT MODEL. Choose your image file then upload.
If you wish to render for other people. Sad to say I have encountered the same problem and according to the support I received. You can upload by going to the desired model and scroll to comments section. You will be able to see "Attach a file" by using this you will be able to share renders to that specific model. It will be visible in the comments section.
But when I did use this the render I attached did not and up-till now has not appeared on my rendering tab. I hope this answers your question.
I trying for both. If I am going to render for other people. How do I upload in the rendering tab?
You cannot upload renders of other people's CAD Model anymore as GrabCAD removed that option. You can now only share your renders in the comment section of other people sections.
To upload renders for other people's model, use the add file link where you add a comment :)