But the message says it's not possible to create a new port profile because you're using an existing name. However, you can link an existing port profile to another network without any problems.
Are you trying to use an existing port profile?
I am not a Cisco Meraki employee. My suggestions are based on documentation of Meraki best practices and day-to-day experience.
Please, if this post was useful, leave your kudos and mark it as solved.