Try giving a different project name, might be Aa is case sensitive, in the error it is written that it is being used by another process.
Do you have m2ee_log.txt open in Notepad? It may need to be closed before you can start the server.
If you are using software like Microsoft One Drive this can cause problems as it is trying to backup files that are being created and manipulated as part of the deployment process. The solution is to move your Mendix application out of the file system that is being backed up by One Drive.