If you have trouble with accessing the SVN, the trouble shooting guide from another lecture might be helpful.
As long as your repository is empty the SVN Repository Exploration perspective might show an error “Authentication error.”, “svn: PROPFIND of '/repos/IAI_Software/se': 403 Forbidden (https://svn.iai.uni-bonn.de)”. Try committing a solution. This should still work and the error message should be gone.