Asset Browser
Assets that are downloaded from Maxon servers are saved to the file path defined here. If you don't modify this path you will be able to access these assets with future C4D versions as well without making any additional changes and without having to download them again.
You can also define custom paths if you like.
Assets already downloaded from Maxon can be removed using this command. They can be downloaded again in the browser at any time.
At the right of the button you will see the amount of memory the downloaded assets require. This memory can be freed up by clicking on the Clear Downloaded button.
Click on the Update icon at the far right to update the memory display if you've deleted or addes assets.
Some assets might not reflect the license you are currently using. These will normally be hidden and can be displayed in the Asset Browser by enabling this option. This option can also be enabled/disabled in the Asset Browser's View menu.
Defines the size with which the previews should be saved, internally. The maximum size can be displayed in the preview window if the preview window is scaled large enough. The internal database will, though, swell quickly in size if too many large previews are saved.
These are the Asset databases. All directories that are define here will be searched for assets. Assets that are stored in this location will be listed in the Asset Browser or Node Editor and will be found by scenes that use the respective asset(s).
You will find more information about how to use this GUI element here.