is there a way to import large existing models in the online version?
Download the model file and then drag the selected file into the modeling space.
If you have the SketchUp file existing on your computer, you can just drag the file into the model space. That’s what I did here. The .skp file is nearly 31 Mb.
If you want to open the file and retain any scenes that you may have set, load the app and in the Home Tab, click ‘Open.’ This will load the SKP file. From there, you can download your progress, or save the file to Trimble Connect.