As this is a graphical issue that appears sometimes, you can simply enter your email address or user ID, then press 'Tab' on your keyboard, type your password and press 'Enter' on your keyboard.
Sometimes, you need to enter user ID then press 'Enter', then type in your password and press 'Enter'.
- Close any running Autodesk programs.
- Rename the folder C:\Users\<username>\AppData\Roaming\Autodesk\ADUT to ADUT2
- Rename the folder C:\ProgramData\Autodesk\ADUT to ADUT2
- Go to C:\ProgramData\FLEXnetand rename the files .data to old.data and .data_backup to old.data_backup
- Restart the product - it will recheck the license and the oxygen screen will appear
- Type into the oxygen login window the username (1), password (2) and clicked on the confirm button (3), see image below.
- Product launches successfully and is activated.
- If product is relaunched, the oxygen window does not reappear.
Also deleting *tsf files can help and fix the issue with the login window. The exact steps of deleting *tsf files can be found under this link.