Passcode

Yes, you did. In this case, that would be requesting a firmware password.

If you can't remember your firmware password, schedule an in-person service appointment with an Apple Store or Apple Authorized Service Provider. Bring your Mac to the appointment, and bring your original receipt or invoice as proof of purchase.

Ref: Set a firmware password on your Mac - Apple Support

So, you don't know your user account password for this Mac ... correct?

If so, then see if this support article can help: If you forgotten your Mac login password - Apple Support

Passcode?

Where are you being asked to enter one:

• At the logon screen?
• At boot up?
• Somewhere else?

Ok, then follow the steps in the provided link.

You're very welcome. I hope you get it worked out.