Hi there stigc56,
We understand you're storing documents in iCloud Drive on your MacBook Pro, and you're having difficulty accessing the files stored there, although you have sufficient iCloud storage space available. We're glad you've taken the time to connect with us here in Apple Support Communities, and we can provide some guidance.
"When you add your Desktop and Documents to iCloud Drive, all of your files move to iCloud. On your Mac, you can find the files on your Desktop and in your Documents folder in Finder under iCloud."
Have a look at the 'On your Mac' section of this support article to learn more:
Access and manage files in your iCloud Drive
Also, you can save iCloud Drive files locally by following the steps in the 'Work with iCloud Drive files offline' section of the link above.
Next, did you turn off Desktop and Documents recently?
"When you turn off Desktop & Documents Folders, your files stay in iCloud Drive and a new Desktop and Documents folder is created on your Mac in the home folder. You can move files from iCloud Drive to your Mac as you need them, or select all of your files and drag them to the place you want to keep them." Take a closer look at the 'Turn off Desktop and Documents' section in this link for details:
Add your Desktop and Documents files to iCloud Drive
We hope this information is helpful. Don’t hesitate to let us know if you have any more questions.
Take care.