I am getting the same error when trying to install ps-pulse-secure-mac-9.0r4.0- Invalid checksum
I tried downloading again from the site and got version
Was able to get to the point I see the package, but when trying to open get an error:
"PulseSecure.pkg" can't be opened because Apple cannot check it for malicious software. This software needs to be updated. Contact the developer for more information."
Found this article https://kb.pulsesecure.net/articles/Pulse_Secure_Article/KB44321
where it explains the workaround by changing settings in Security & Privacy/ General