The account you signed in with does not have access to this file

Hello ​@Rachel38744444mgd4 

I’m sorry to hear about your experience. Our product team is currently investigating this issue. Would you mind trying the following steps and letting us know if they help:

• Go to System Settings > General > Login Items > Enable CC Library.
• Relaunch Illustrator

If it’s already enabled, remove it from the items, re-enable and then quit and relaunch the Creative Cloud Desktop app and Illustrator to see if it helps.

If the problem persists, try enabling Full Disk Access for the Creative Cloud Desktop app from system preferences, restart your computer and relaunch to see if it helps.

If the steps above failed, try the following steps and let us know how it goes:

• Close all Adobe applications
• Remove the Creative Cloud Desktop app, Core Sync, CC Library and Illustrator using the Creative Cloud Cleaner Tool (https://helpx.adobe.com/creative-cloud/kb/cc-cleaner-tool-installation-problems.html)
• Reinstall the Creative Cloud Desktop application (https://helpx.adobe.com/download-install/kb/creative-cloud-desktop-app-download.html)
• Reinstall and relaunch Illustrator

Looking forward to hearing from you.
Anubhav

​@Rachel38744444mgd4 Is it this message: ““Can’t open file. The account you signed in with doesn’t have access to this file”?

There were a few more posts like this during the past few days.

I agree with Bobby that it is worth trying to download them from the Files section in the CC app.

Are your files stored in a cloud location? If you haven't already tried this step try opening the Creative Cloud desktop app, going to the Files section. Hopefully your files will be properly synced and visible there. If the files are visible try downloading the file that won't open to your computer's hard disc. Then try opening the file in Illustrator from that local disc location.