Hummingbird cannot activate - fatal error

Hi!

I've been trying to install Hummingbird on my woocommerce-shop http://www.badmiljo.se since yesterday. Sadly I keep getting the same error.

This: Fatal error: Class 'WP_Hummingbird_API_Service_Uptime' not found in /www/webvol15/dz/flgz36zyortl80w/badmiljo.se/public_html/wp-content/plugins/wp-hummingbird/core/api/class-api.php on line 7

I've been reading people having similar issues caused by their server running an old version of PHP. I contacted my hosting provider who informed me my server is running on PHP 5.6

Could you please help me find the issue that is causing the error upon activation of Hummingbird?