The Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter is bidirectional and can enable Thunderbolt 3 computers to use Thunderbolt 2 devices, and Thunderbolt 2 computers to Thunderbolt 3 devices. HOWEVER, it only supports self-powered Thunderbolt 3 devices, such as the CalDigit TS3, TS3 Plus, TS3 Lite, T4 Thunderbolt 3 RAID. It is NOT compatible with Thunderbolt 3 devices that draw the power from the computer, such as the CalDigit Thunderbolt 3 Mini Docks and CalDigit Tuff Nano. The bus-powered Thunderbolt 3 device is NOT compatible with this Apple’s adapter.
In order for a legacy Thunderbolt 1/2 Macs to use a bus-powered Thunderbolt 3 device, you can use this Apple adapter to connect to a dual-port Thunderbolt 3 device such as the CalDigit TS3 Plus Dock then connect the CalDigit Thunderbolt 3 Mini Dock or Tuff Nano to the downstream Thunderbolt 3 port on the TS3 Plus. The maximum number of external displays support from the entire Thunderbolt chain is 2 and is limited by the computer and GPU.
About the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter