How can I access the SVN repository?

Access to the repository, regardless of whether SVN or Git, is only possible by http. Is enabled SSL encryption in the hosting, access can also be made via https.
This example here show the access using the Tortoise SVN client on an SVN repository.
Den Pfad zum gewünschten SVN Repository finden Sie in Redmine bei den Einstellungen des Projektes.
The path to the SVN repository can be found in Redmine in the settings of the project.

There, the path is listed with the SVN repository can be reached.

Here, that would be the Url: http://redmine21.saas-secure.com/svn/svntest2
In Windows File Explorer now just right click with the mouse to bring up the TortoiseSVN context menu into view.

Enter the Url to the repository in the url field. In the field Checkout Directory, enter the local folder.
Clicking the OK button the SVN client starts to access the repository. If for access a user name and a password is needed, this will be queried.
After a successful checkout the repository contained files will be found in the target directory.