It is not on the Actisense site.
Just Google PL2303HXD&G_Mac Driver and you will get to several relevant sites.
If you still have a problem I can send you a copy to your own web address.
My macs do not work without this driver.
Have you loaded the serial drivers for Mac, ie PL2303HXD&G_Mac Driver_v2.1.0_20210?
These should be available on line.
Fred