Unsure if this is the same problem I'm having, but here's my error log for an issue that also is related to cloth config 6.1.48: https://pastebin.com/x7WQ3kCM

I had the same issue, the fix is incredibly simple to do:

Use 7zip to open the archive, open the fabric.mod.json file, and find the 5 near the bottom in "cloth-config2": "5.x". Change this 5 to a 6 and save the file.
This is as simple as a single character change in the mod jar. I'd make a pull request to fix this if I wasn't busy.
The creator should do this, and should consider instead do something like 5.x+ so that the compatibility could work with older versions.
I would include my fixed .jar but github does not let me upload that.

Had the same issue and can confirm @griffin4cats solution fixed it.