To install any out of release script, it is easy :
Create a custom script folder in your hard disk (in my documents folder for example),
Unzip all files you can get (for example, SHOAIP, EZsuite... ) and keep them in each subfolder (better for update)
Under Pixinsight, Script-->Feature Scripts--> select the custom folder in my documents, then all recursive folder inside will be analyzed and every scrip will be installed.
If you have to update PI core, uninstall, then, you need to only add this custom folder 1 time after reinstalling.
If you have script update, just change them in custom folder. Maybe regenerate if needed
I run this since the begining of PI scripts. I never got any issue, Windows or MacOS !