Collaborator v9.3 server cannot connect to VisualSVN Server v3.4

Hello,

We have a Collaborator v9.3.9300 server that has to support us for code reviews on a SVN codebase hosted on VisualSVN Server v3.4.1 based on SVN 1.9.

On the server machine, we have installed TortoiseSVN 1.8.13, which is compatible with our server, we use it on every dev machine.

Trying to create a new Version Control server-side for this VisualSVN server has never worked:

 svn Executable: C:\Program Files\TortoiseSVN\bin\svn.exe

 Repository URL: https://ourserver/svn/ourproject

 Username: ourbuildaccount

 Password: *******

Testing the connection always fails with an authentication error:

Error: Invalid input: Version control server configuration error: Could not create valid Subversion configuration based on configured repository url: svn: E175013: Access to '/svn/chinook2/Chinook2' forbidden

Our build account comes from LDAP, it is part of a domain, so I have also tried to enter as Username: "OurDomain\OurBuildAccount", but it ends with the same error.

Logging in to the server machine and trying to query our SVN server with the TortoiseSVN command line client installed works.

We have another Collabnet server on 1.6 with the Collabnet client 1.6 installed and this connection works fine.

The server logs are not giving additional information, authentication failed and that's it:

com.smartbear.ccollab.controllers.AdminScm - Error trying to validate version control server configuration
com.smartbear.scm.ScmConfigurationException: Could not create valid Subversion configuration based on configured repository url: svn: E175013: Access to '/svn/chinook2/Chinook2' forbidden