(I am still also asking the SHA-256 hash of the script.)
What's this and how do I do it?
You could have googled to get instant answers but anyway nullius is asking you to encrypt the script file using SHA-256 encryption algo which you can effectively do it online using
https://hash.online-convert.com/sha256-generator if you're not very familiar with a command line tool.After conversion,you can send the HEX/base65 encoded generated hash to nullius.