If you're using the full edition of Cinema 4D, you can render straight out of the Picture Viewer instead of exporting to After Effects. Here is the fastest method:
Open Edit Render Settings... (Ctrl + B / ⌘ + B)
These are your export settings, where you can set your height, width, and how many frames you want to export. See Cinema 4D Lite export guide for more details on these options.
Open the Picture Viewer with (Shift + R)
Your export will start rendering. How long this takes depends on your settings and the complexity of your scene.
When it's finished, go to File → Save As... to choose your export file type.
The options for exporting directly from Cinema 4D are more limited than what's in Adobe Media Encoder. If you're exporting a video, you may need to convert it to an .mp4 encoded with H.264 in Adobe Media Encoder to upload it successfully on social media.