nothing wrong with that. you then need to figure out what the server is complaining about and fix that.
A 500 error is the server saying: "Your site told me to do THIS, but the server config files say I should do THAT. So im just going to do nothing until you fix something."
* copy the files to the new server.
* copy the database to the new server.
* update the /data/config/conf.php with the site domain name and the database password.
For you, you want the default setting for them to be OFF when new profiles sign up, so uncheckt the checkbox in the GLOBAL CONFIG setting so new profiles do not have approval on.
Then you can use the TOOL to change all profiles in either direction.