Hi @MURAT AKDENIZ,
Thanks for posting. I believe I've seen this issue. Are you part of an enterprise or educational facility? If so, Creative Cloud sync was removed last year. If you didn't retrieve your projects and sync them with the device at that time, then I believe those projects can't be retrieved currently. Sorry you weren't aware of this issue in advance.
Take Care,
Kevin
Kevin Monahan - Sr. Community and Engagement Strategist – Adobe Pro Video and Audio