What product versions are supported?

All paid IntelliJ-based IDEs are supported from version 2019.1 (released in Spring 2019.)

All Community Edition / Educational Editions of IntelliJ-based IDEs are supported from version 2019.3 (released in Winter 2019.)

Most of the Marketplace support works in 2018.3 version (Winter 2018), but it's not officially guaranteed.