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.
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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.