With some Subversion servers authorization may fail when accessing the repository from IntelliJ IDEA. In this case please try to add the following VM option to IntelliJ IDEA:
-Dsvnkit.http.methods=Basic,Digest,NTLM
On Windows you can add it in IDEA_HOME\bin\idea.exe.vmoptions file, on Linux add it into IDEA_HOME/bin/idea.vmoptions file, on Mac see the related article.
This bug bit me. It accepted my login after about 10 attempts every time, but whether it actually did all the work, I do not know. Thank you for the heads-up!