Don't know administrator name or password

Johnnygonzo wrote:

So who is the administrator? Me the owner of the mac. If so, what is my administrator name and password.

If you are the owner, presumably you are the Administrator. macOS User Guide explains administrator as follows:

"An administrator can add and manage other users, install apps and change settings. The new user you create when you first set up your Mac is an administrator.

Your Mac can have multiple administrators. You can create new ones, and convert standard users to administrators.

Don’t set up automatic login for an administrator. If you do, someone could simply restart your Mac and gain access with administrator privileges. To keep your Mac secure, don’t share administrator names and passwords."

Since you are the owner, you had to setup the "name and password," which can be found in System Preferences>Users & Groups. Change Users & Groups User preferences on Mac explains:

"Important: If you’ve forgotten or need assistance with a login password, the following topics may help:

• If you forget your login password on Mac
• Reset your Mac login password
• Learn how passwords are used on Mac
• Change your password, user picture or automatic login items on Mac"

Who owns the Admin Account on that computer?

A "Guest" user cannot install applications without the permission of the Admin User.