No compatible PowerCLI version is found for vCenter Server 9.0.
"Product Interoperability Matrix" indicates vCenter Server 8.0 or prior are compatible with PowerCLI.
https://interopmatrix.broadcom.com/Interoperability?col=299,&row=2,
VMware vCenter Server 9.0
"VCF PowerCLI" has been available since VCF 9.0 was released.
"VMware PowerCLI" is compatible with vCenter Server 8.0 or earlier.
For vCenter Server 9.0, "VCF PowerCLI" compatibility matrix should be checked instead of "VMware PowerCLI" matrix.
https://interopmatrix.broadcom.com/Interoperability?col=2301,&row=2,&isHidePatch=false&isHideLegacyReleases=true