Wiring of USB 2.0 hub using a USB-C connector
Your computer does not see your device/hub because the CC1 (communication channel) pin A5 is not wired (or wired incorrectly). For the cable to be recognized as a device/hub, the CC1 pin must be pulled down with 5.1k resistor. Your connector even might have a placeholder for this resistor. Just make sure the CC1 is not pulled high to VCC, this will make the plug as "host", and your computer will switch into device mode (if it supports it).

This is the standard and fully legal captive cable configuration, see Section 3.4.3 and Table 3-11 of USB Type-C specifications.