Hi Shirley,
Sorry for the late reply.
By letting users add links without enrolling on the course, does it mean that anyone visiting the website can add links?
If this is the case, IMHO it is not a good idea. However, if you want to manually let users you trust to do the job, you can assign appropriate Front Page roles to them, for example: Manager without them having to enrol to the course.
I hope this helps.
Kind regards
Adi