Would you please try follow steps:
1. Quit Adobe Creative Cloud , Extension Manager and all Adobe products.
2. Rename opm.db to opm.db.bak in
Windows: c:\Users\<yourname>\AppData\Local\Adobe\OOBE
MAC: /Users/<yourname>/Library/Application Support/Adobe/OOBE
3. Launch Extension Manager CC.
4. Install your extensions.
Please let me know if it does not help.
