I installed dftly Time Tracker into my Salesforce org. But I have not received an email with the App Key. Why is that?
The reason you did not get the email was because, in the Sandbox, the email access level is set to 'System email only'. To send email other than system general emails, you need to set the Access Level to 'All Email' and save the configuration. By default in Sandboxes, the Access level is set to 'System Email Only'.