The script works the same on all platforms.
That means you missed something in the documentation. Probably the step where you say Siril where the script is.
Yes. The problem got resolved. As suggested by @kichererbse , the issue was the right directory of storing the script. I had downloaded the Seestar script in a different folder and given the path in the Preferences. However Siril requires the script to be exactly in the same folder where the scripts are originally stored. The issue is now resolved. Thanks everyone for the help !