Using your web browser, go to the Firefox browser add-ons store and enter “Calendly” into the search box.
Select Add to Firefox and follow the instructions that appear to grant Firefox permissions. When installation is complete, the Calendly icon appears at the upper right side of your Firefox browser window.
Click the Calendly icon at the upper right side of the Firefox browser, select Log In and enter your Calendly username and password.
Check to see if you have content blocking enabled in your browser:
Enter “about:preferences#privacy” into the Firefox address bar.
Scroll down to Cookies and Site Data and select Manage Permissions.
At Address of website enter “https://calendly.com”, then select Allow.
Select Save Changes.