I might suggest rendering an image sequence - you can start/stop literally anywhere, and AE will know which frames already exist, as long as you continue exporting to the same folder. If you need to make any changes along the way, just re-export that section.  Once your sequence is done, you can slap that back into AE, or into Premiere, or whereever else, and marry it with audio, do final color, etc.  Note: Avoid PNG for this task. The file size is smaller, but you'll pay for it in time, both in creation and when using the file again later. EXR is my go-to format here.  ... View more

I never noticed this gap in the tutorial, but he also never really stops on the few frames where this gap is visible. So I followed a hunch and ... for what it's worth, Manuel's project (which you can download from Gumroad) has the same shadow gap, if you look for it. After bringing this up with a member of the Ae team, it sounds like this is actually a limitation of the C4D Renderer - no contact shadows!  In Manuel's tutorial, cranking up the Diffusion on the shadow seems to hide it well enough, so that's what I'd recommend in your case. Adjusting the timing of the actual page turn may also help hide this, since it's really only visible on those few frames when the page is on-edge to us.  The Beta version of Ae has an additional new 3D rendering engine, which enables some new lighting & shadow behavior. You could certainly explore that as a solution as well, though it'll somewhat change the lighting setup from what Manuel does.  ... View more