Unable to connect to server connection failed: connection to server at 127.0,0,1 post 5432 failed could not receive data from server

I installed PgAdmin 4 to my MacBook Pro Sonoma version 14.4.x and once it opened I attempted to create a server or register a server and I have host name/address as localhost, port 5432, maintenance database of postgres and the username as the username of my machine, but I get an error message saying Unable to connect to server: connection failed: connection to server at 127.0.0.1 port 5432 failed: could not receive data from server: Connection refused. What could be going on?