SVN updates (for all versions of Tiki) is no longer supported. You should get your updates from https://gitlab.com/tikiwiki/tiki. See also: Tiki Version control history.
You can subscribe here: https://sourceforge.net/projects/tikiwiki/lists/tikiwiki-cvs
For historical reasons, it's called cvs, and it's not worth the hassle to change it. Ref.: Tiki Version control history
Here is also a great source of code activity updates: https://gitlab.com/tikiwiki/tiki/activity