This a standard AspNetCore application so running it should not be a problem.
Remarks: The apply for the course method has a relative address: /api/courses/{courseid}/apply
For example: /api/courses/9d401e07-3018-4aef-a62e-ca0ec308e59e/apply
The courseid is a Guid and this is a POST method requiring something like this in the body: { "UserId": "456c5e31-b593-4076-aa24-0423a9d63438" }
The data is currently persisted only in memory, but to find the data without looking through the code several methods were also exposed:
[GET] /api/users -> to find all the users and their Guid Ids
[GET] /api/courses -> to find all the courses and their Guid Ids
[GET] /api/courses/{courseid}/getapplied -> allows us to check which users have applied for the course
For example:
/api/courses/9d401e07-3018-4aef-a62e-ca0ec308e59e/getapplied