Students cannot use Turnitin or its plagiarism checking functionality unless an assignment has been set up by a lecturer in a Myplace class page.

Staff could make submissions for the sole purpose of plagiarism checking via a 'test' or other (non-registry) class, by simply adding a Turnitin assignment when editing the page (Go to Myplace page, 'Turn editing on' then select 'Assignment' from the 'Add an activity or resource' link - the assignment settings are defaulted to have Turnitin enabled, but the originality report not available to students - all of the assignment settings can be changed according to requirement)  Students can then 'submit' an assignment and an originality report will be generated.  (The member of staff can also submit his/her own work in this way - note that the eye icon can be used to hide the assignment from view of students in the class if preferred.)  

You cannot submit on behalf of someone else, as each Turnitin user must accept Turnitin's End User Agreement, and must also tick the University of Strathclyde submission statement to agree that the submission is all their own work and may be subject to plagiarism checking.  

Staff can set up a playground Myplace class page if using a separate non-registry class is preferred.