Converting a script designed for the App for one compatible with Automations could require no changes to the code, or extensive changes to the code. It depends on the script.
Check the scripting documentation for the functions that work in Apps but not Automations (and vice versa): Airtable Scripting
Could you describe more about your use case where you want to automate the running of a script that requires user input? As @Kamille_Parks indicated, automations run in the background, so I’m struggling to think of a use case where it would be desirable for a background operation to require/request input from the user.