can connect with root, not user_act

I try to logon with the user created in the database I can’t connect. I get the error: Error establishing a database connection

If I change the ‘DB_USER’, to ‘root’ with no password in the wp-config.php I get right to the configuration screen.

I have XAMPP installed on a Mac mini with OS 11.3, WordPress is installed in a subdirectory.

Further, I created a PHP connection test file and I can’t get in with this either.

<?php
$servername = "localhost";
$username = "mcsga_user";
$password = "XXXXXXXX";

// Create connection
$conn = new mysqli($servername, $username, $password);

// Check connection
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
} 
echo "Connected successfully";
?>

this is an export of my user that has access to the mcsga database.

GRANT USAGE ON *.* TO mcsga_user@% IDENTIFIED BY PASSWORD ‘*87AE701A070C45E7172C5411D7ED3EFB9276CC8A’;

GRANT SELECT, INSERT, UPDATE, DELETE, CREATE, DROP, REFERENCES, INDEX, ALTER, CREATE TEMPORARY TABLES, LOCK TABLES, EXECUTE, CREATE VIEW, SHOW VIEW, CREATE ROUTINE, ALTER ROUTINE, EVENT, TRIGGER ON mcsga.* TO mcsga_user@%;

I don’t have any idea what’s going on.