I am failing z-parameters, but I don't know why
The Z parameters are the open circuit parameters.  So, for example,

$$Z_{21} = \frac{V_2}{I_1}, \, I_2=0$$

But, for the voltages and currents given, \$I_2\$ isn't zero.  In fact, it says this in the problem statement:


  A two-port network is driven at both ports...


The voltages and currents given can't be used to directly compute the Z parameters as you are attempting to do.

However, recall that, in general:

$$V_1 = Z_{11}I_1 + Z_{12}I_2 $$

$$V_2 = Z_{21}I_1 + Z_{22}I_2 $$