I can see this error message on the 6-Publish page
This message appears when you have unassigned students in the course where this activity belongs to. Unassigned students are those who do not belong to a section and team. These students will not be able to participate in a team-test/activity.
Here's what you need to do
Click the number of students
You'll be able to see the names of the students who are not assigned to any team and section. If you think these student accounts (like your own student-account) shoulddn't be in a team, then go ahead and publish.
Click "here" in the red box.
Click "here" in the red box.
You'll be taken to the STUDENTS tab of your course.
Find the "Unassigned Students" table in the students list.
Click "Organise Students" button
"Organise students" will allow you to make changes to the student's team assignments.
Clicking this button will also allow you to :
add new teams in a section
create a new section
rename team and section
view student details, etc.
Drag and Drop the student into a team
Click on the student, drag it to a team and drop it there.
Click "Update" to save changes.
Now that all students have been assigned to their respective section and teams, click the "Update" button to save your changes.
***NOTE
You can leave student accounts (For example, your own student account) as unassigned. You'll still be able to publish your activity.
Now you can publish
You can go back to the activity and "Continue Setup" and publish the activity.