Miscalculating the nominal power using nominal current and voltage of a VFD
The induction motors come in standard sizes and nominal powers, for example 2.2kW , 3kW, 4kW, 5.5kW, 7.5kW, ...

Those power are the mechanical power, delivered at the output shaft: \$P=M\cdot\omega\$

You can use your inverter with 5.5kW or 4kW induction motor, it depends on the load characteristics. Whenever the load is constant, then it can drvie a 5.5kW motor, but if the load is dynamic with high torque peaks, then a 4kW motor is suitable.