i know this late response but it could help someone
I don't know the real cause of your problem, but I recommend testing the SQL Server name first using the SQLCMD command in PowerShell. If it connects successfully, then the SQL Server name is correct, and there may be other issues to address:
You might need to create the SSIS catalog (SSISDB) if it doesn't exist
You may need to create the appropriate folder structure within the SSISDB
Check the permissions of the user account you're using to ensure it has sufficient access rights