[PROBLEM] HDD not dected

[Tim Curtis]

Most likely the Zero's total USB bus power is not sufficient to support the 4th connected device but as @fdealexa mentioned you should first connect just the Toshiba drive and verify that it's recognized and functions correctly.

Once thats done u could try a powered USB hub, they are readily available for example:
https://www.amazon.com/AmazonBasics-Port...r=8-3&th=1