Describe the feature

I want to use phantom membrane on framed blocks so I can walk through.
But I can't open the config to enable it.

What specifically do you mean with "can't open the config" in this case?
The config file is located in <world folder>/serverconfigs/framedblocks-server.toml. You should be able to edit that file with any basic text editor such as Notepad on Windows. You may just have to right-click the file and select "Open with" instead of simply double clicking the file.

Closing due to lack of feedback. I assume the above response answered your question.

Is this setting available in the latest version from curseforge? I don't actually have a server config, I have a client and common config, and the common config only has the setting for fireproof blocks. Is there somewhere else to get a newer version of the mod?

Nevermind. I actually read what you said and I realized I've been looking in the wrong place.