Is there a size limit to the disk space or total number of assets that can be shared at one time, in one link when using the “External Link” function?
There is no imposed size limit. However, the files are delivered as a ZIP archive, which can take time to compress when larger files are included. Depending on the network, if the ZIP stream takes too long to download, a browser might timeout on a request.
macOS default ZIP unarchiver doesn’t handle ZIP files larger than 4GB in size that are made by third-parties (i.e. macOS can only handle large ZIP files that are created with the macOS ZIP utility). Use a third-party app like Keka (http://www.kekaosx.com) to extract large ZIPs on macOS workstations.