I can' connect to SQL Server Manegement Studio 20 in Unity

QL Error: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 40 - Could not open a connection to SQL Server)
A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 40 - Could not open a connection to SQL Server)
UnityEngine.Debug:LogError (object)
HighScores:DisplayHighScores () (at Assets/Scripts/HighScores.cs:44)
HighScores:Start () (at Assets/Scripts/HighScores.cs:16) 

I tried : 
private string connectionString = "Server = localhost; Database=GameScores;Integrated Security = True; TrustServerCertificate=True";
and 
Data Source=DESKTOP-U5TLUJP;Initial Catalog=GameScores;Integrated Security=True;TrustServerCertificate=True

```How can I find the correct connection string for my database? I do not use a password or anything. Normally, I can connect directly when using MSSQL.