Hi, I'm Bernard. I'm happy to help!
BitLocker is another layer of security protection for the PC. Are you the only one signed to that device, or is there a previous owner of the PC? If there is, you need to ask the previous owner for the BitLocker key, or direct them to the link below.
If you are the only one, or there is another account in there, go to:
https://account.microsoft.com/devices/recoverykey
To check for the BitLocker recovery key.
For reference: https://support.microsoft.com/en-us/windows/find-your-bitlocker-recovery-key-6b71ad27-0b89-ea08-f143-056f5ab347d6
Note: This is a public forum. I may respond within a short period of time, but I apologize in advance for any delays. I am simply a fellow user trying to provide helpful insights and information.