Hi @Lisa71 ,

if credentials are password it will run as the user 

If no authentication is required, the script runs in the context of a "Guest" user.

example

I have created a sample scripted rest api which creates an incident

called the api without credentials

when no credentials is opted it runs the api with Guest user permissions

Please mark my answer as helpful/correct if it resolves your query.

Regards,
Chaitanya