Hi,
I think you’ll need to work in Python to get what you want… The package BumbleBee allows you to get inside and have a look, for example by using the Python in the ‘Write Excel’ node and adding 'Password = “test” to the SaveAs, I was able to create a password protected file…
wb.SaveAs(unicode(filePath), Password = "test")
This post by @c.poupin & @GavinCrump also discusses how you can create workflows…
Though you may have to play around with the Microsoft Docs…
Best of luck, hope that is useful,
Mark