I’ve just put a few notes on the help wiki

Here’s a summary:

1. Go to your Subversion Homepage
2. Under the heading Export a Subversion Repository click on Export a Subversion Repository or just head straight to the export form
3. Pick the repository that you’d like to export.
4. Click on Export
5. An exported file called <repositiry name>-dump.gz will be created in your Subversion home page under the section Files Available for Download

So, you’d want something like a “nightly dump” of your repository ?

Easiest thing to do is make your own backups and integrated it with webhooks