The developer tools in the browser allow you to view the headers of requests to the server.
Go to the page with Basic authentication and open the developer tools (press F12). Then click the Network tab.
This is where your requests to the server will be displayed.
Now without closing the console, authorize on the page. After authorization, your request will appear in the console. We can open it and see the headers.
Request Headers are the headers that your browser sent to the server. Among them is the Authorization header.
This header, as you already know, contains the login and password, which means that it will be different for different credentials.
Find out the content of the Authorization header if you enter the following credentials: Mike(login) and 12345678(password).
For example, in our case (login: Admin, password: 2425) the answer would be: Basic QWRtaW46MjQyNQ==