You can use the Group Policy Editor to set this option.
1. Press the WinKey+R to display the Open dialog.
2. Type gpedit.msc in the Open: box and click OK.
3. In the Group Policy Editor, navigate to Computer Configuration/Administrative Templates/Windows Components/BitLocker Drive Encryption/Operating System Drives.
4. Right Click the Require additional authentication at startup policy and select Edit.
5. Click the Enabled option.
6. In the Options section, place a check mark in the Allow BitLocker without a compatible TPM option.
7. Click Apply/OK and exit the Group Policy Editor.