I forgot my security and privacy password

If you cannot find your password you will need to reset it with a new, different one using the link below. After this is done I strongly suggest that you write the information down and save it in a secure place for the next time you need it.

Change or reset the password of a macOS user account - Apple Support

Unless you deliberately created a different one, it is likely to be your old Mac Login password (not to be confused with your Apple-ID anything).

Blocked from using MAC Pro 2019 tower for 4 months.

due to Apple not accepting password. Very frustrating

experience. Is this caused by iCloud?

3 Apple stores NYC could not retrieve access to password.

What can be done to alleviate this problem in the future?

Apple is not simply being 'uncooperative' about this. Your password is not stored on your Mac, 'in the clear'. Only the encrypted version is stored. Not even the password length is known.

Instead, as you enter the characters, what you type is encrypted as you type, and when you press return, the fully encrypted typing is compared to the stored encrypted password. The only thing that can be determined is, ¿Was that it?

Apple can offer you the service to erase everything on your Mac, leaving it clean to be set up again from scratch. Requirements for this service are the original bill of sale showing the serial number, or for a used Mac, a collection of bills of sale showing the chain of ownership, including serial number, back to the original purchase.

As has been noted above, it is NOT possible to retrieve a password. You must go to the site provided above and set up a new, different password. Have you tried that yet?