Your students need to buy the Student's Book special pack with Access Code from the bookshop.
The Access code can be found on the inside cover of their book.
ISBNs for Students' Books with Access Code for Online Workbook:
MyCosmicLab access is free for teachers who have adopted Cosmic as the main B1,B1+ and B2 course in their exams classes. Students will need to buy the access code version of their coursebook. Please contact your local Pearson representative for more details.
MyCosmicLab is the online workbook component of the B1, B1+ and B2 course Cosmic. It is not a course in itself. All the content is integrated with each unit of the course and it is intended to be used only with this course.