Did you have show invisible files enabled when you transfered the files? Please ensure that the hidden .htaccess file ihas been transfered to the root of your public folder on the server.
You’ll have to identify whether the 500 error is being generated by Kirby because of a problem in PHP code, or by Apache because of a problem in Apache configuration.
If the error is generated by Kirby: you’ll need to turn on the debug option temporarily to be able to see more info about what PHP error or exception happened.
If it’s generated by Apache, you’ll need to find your Apache error logs and check the error messages there.
(Apache 500 errors tend to look like very plain pages with text aligned to the top left of the page, or completely unstyled. The default 500 error page that Kirby uses has centered text and a link to the Kirby docs.)
You can try requesting a specific path on the site (even if it would be a 404 normally), like https://domain/my-test-path, then in the Apache logs at the end look for a line that shows /my-test-path and look at what the error says.
If you can’t find the correct log file or the Apache logs don’t have enough information about what happened, you may need to look at your host’s documentation and/or reach out to their support about ways to get more debugging information.
Typically, Apache errors for PHP sites tend to be about Apache rewrite configuration not working well for that specific Apache server, resulting in infinite redirects, or requiring a specific RewriteBase value.