Make sure you are using the latest version of WordPress and at least PHP Version 7.4 (preferably 8+). Using versions of PHP older than 8 is not recommended due to security and performance issues in old versions of PHP. 

Download the plugin file your account on latepoint.com.

Now go to your WordPress admin and upload this latepoint.zip file to your plugins page in admin.

Don’t forget to activate it. Once it’s activated you will be presented with a Setup Wizard, that will guide you through setup process like adding agents, services and setting work hours.