need password for software update

If you have forgotten your mac login password, see this link and follow the instructions

https://support.apple.com/en-us/HT202860

You need to use the password for the administrator account, that will be the first account you have ever made on the mac

That is Normal that the User must manually input the Password for the Admin Account of this computer.

Nothing new about that.

Reset Computer Password  for the Administrator Account Password

Intel Computer

1 - Restart computer and immediately hold Command + r keys

2 - Top Tool Bar >> Utilities >> Terminal

3 - Type resetpassword as one word and no spaces

4 - Press Return key

5 - Follow the prompts and remember the New Password

Apple Silicon M1 Computer 

1 - Choose Apple menu > > Shut Down.

2 - Press and hold the power button on your Mac until you see “Loading startup options.”

3 - Click Options, then click Continue. 

4 - Top Tool Bar >> Utilities >> Terminal

5 - Type resetpassword as one word and no spaces

6 - Press Return key

7 - Follow the prompts and remember the New Password