eujjRener the swiftmailer line is only a warning for developers in the Composer output. You can ignore it. The remaining of the Composer output should let you know if it was successful or not.
If you are not sure if the installation was successful or not, please send a screenshot/copy of the file listing in the directory after running Composer and/or the Composer command output.
If the files have been created, you can proceed setting up the DocumentRoot to the public folder and accessing the web installation wizard where you will see if any dependency failed to install or is missing from the server.