The incompatibility between the client and server is fixed in Pulse Secure Connect / Pulse Policy Secure 9.0R3 (for browser based Host Checker installations) and Pulse Desktop Client 9.0R3.
For macOS, the OS Check rule was introduced in 9.0R1 so when connecting from a pre-9.0 pulse client to a 9.0 PCS/PPS the error displayed on the Pulse client is the following:
OS Check rule is not supported for installed client.
Please upgrade to supported client version.