Encryption is complex stuff; if you had a problem, it was with that. It sounds to me like you're very ready to use Kubuntu, but maybe need some mentoring for encryption, if that is important to you. Very easy to mess that up if the complex fixes are too much at the moment. Note: at the moment. You learn as you go.

Edit: I don't use ChatGPT, but I have found the google AI that shows up on search, tends to be pretty good at this sort of Linux system problem. Still might overwhelm you with acronyms and such.