Hello,
I suggest you to check with Require additional authentication at startup Group Policy setting and see if Allow BitLocker without a compatible TPM option is checked.
If that option is checked, you can use password else you can enable BitLocker PIN if you've TPM installed (works in Windows 10):
https://www.kapilarya.com/enable-bitlocker-pin-in-windows-11
Let us know if this helps!
Note: Included link in this reply refers to blog post by a trusted Microsoft MVP.