A lecturer wants to grade me based on 'creativity' in a task, how do I succeed?
tl;dr: your lecturer is right in principle. Commit time and effort to your project and try to be creative.

In higher education, students are expected to develop the skills which enable them to apply a number of techniques, compare the results, evaluate their effectiveness, synthesise new methods, or even suggest new approaches to a problem. Your lecturer is right to expect students to be creative. 

In the last decades academia is under an increasing pressure of corporate managerial culture: education is considered as service and students are treated as customers. This creates a new kind of relations. Some students expect to acquire complex skills without spending sufficient time practising them (without feeling overworked) and expect first-class grades without committing themselves to the work required. Some students, supported and encouraged by academic managers, require more strict and deterministic rules to be set for academic assessments, such as precise specification of assessments, past papers to be provided with model solutions, and new assessments to be very predictable. Under this pressure, academics are forced to remove creative elements from their assessments and ultimately from their courses. As the result, many students don't develop the creative, teamwork and communication skills which are important for employers.

Even if your lecturer was not very efficient in communicating expectations, they are right in principle: they actually want you to use education as the opportunity to develop right skills. You want security and a good mark. Your think as a consumer; your lecturer thinks as an educator.

So my suggestion is: trust your lecturer; commit time to the project; try to be creative as much as possible. For this, learn at least 3 different methods to solve the problem, reproduce them, and try to create one more from scratch. Compare the results and present results in an engaging and visual way. Plan at least 5 hours of work for 1 minute  of final presentation or 1 page of final report.