Can we install latest requiring php 7.4 or higher without composer ??

You can install application without composoer and I'm not sure about php 7.4 but it works with php 7.3 / 7.2 / 7.1 as well as

Hello,

The vendor folder with all packages is the download and you don't have to run any composer command.

500 error could be due to various reason and you need to check your server error logs for error details and let me know so that I can suggest.

Thank you