I want to use Negative Lab Pro to convert my negatives but I am on a Lightroom 3.3 plan. I believe I need to be on Lightroom Classic to use plugins. Can I change plans and can I move my photos (with edits) from Lightroom 3.3 to Lightroom Classic (not sure if the images would also be stored in the cloud or on my desktop when using Classic)?
Don't know if you can change plans but you should call Adobe. From what we've heard on the forum, they tend to honor these sort of requests.
As soon as you install Classic (which you can do now) you can log onto the same account and turn on sync and it will download everything that is in the cloud including edits to your Classic catalog. Classic needs all the files to be local so it will need to download everything.