CFbuilder 2018 and SVN plugin

What is "the old url" you refer to? There are many SVN plugins that could work and which each have their own URL. 

To be clear, CFBuilder 2018 and earlier is built upon the Eclipse IDE, and so any SVN plugin would technically be a plugin for Eclipse, which happens to work in CFBuilder. As such, here is a listing of several SVN Eclipse plugins:

https://marketplace.eclipse.org/category/free-tagging/svn 

Granted, SVN has lost favor to Git in recent years, but some do remain and continue to work.

For instance, a prominent one is Subversive, and it's had various versions but the most recent is already a few years old. As an example of "the url" for that, which I just confirmed does work in CFBuilder, is this: http://download.Eclipse.org/technology/subversive/4.0/update-site/. When you read any resource that talks about installing an Eclipse plugin, the same steps apply in CFBuilder.

One last thing: do note that the last update of the standalone version of CFBuilder 2018 (3.2.1) embeds Eclipse verison 4.9, which is from 2018. Just beware of that if you may find and consider plugins that may only work with later versions of Eclipse. (FWIW, you can also install Eclipse on its own and implement CFBuilder WITHIN that new Eclipse as a plugin itself--CFBuilder, I mean. It can EITHER be a plugin FOR Eclipse or it can be the standalone version of CF that EMBEDS Eclipse.)

Hope that's helpful. It can indeed be a bit confusing. (And the next release of CFBuilder will instead be based on VisualStudio Code, which will be quite diffrent.)