Compatible up to version: 6.4 ?

Yes it is

i have 6.4.2 and the new update (today) took the calendar off the site. What do i do?

A first step in troubleshooting any plugin should be to install the Health Check & Troubleshooting plugin. This plugin allows you to view you site as an administrator with all other plugins disabled and using the default theme, while keeping you site fully intact for other visitors. Then you can see if the problem goes away, and enable other plugins one by one to isolate the conflict.

For more information on using this valuable tool, please visit the WordPress documentation.