What version is your development machine running? What version is your server running?
There's likely to be a mismatch
How did you get the Silverstripe code? Did you use composer, or download the zip file?
I used composer to my localhost and then ftp it onto the server
OK. And the PHP version on your local machine?
Including the command line?
Check for multiple versions. I've been caught out before running PHP 7.1 on the CLI and finding the webserver on 7.0
php -v on the command line will confirm