Hey @mms,
Yes, you can use the Spin and Connect process engine plugins with Camunda BPM Run. To do this, you need to drop the appropriate jar archives (camunda-engine-plugin-spin, camunda-engine-plugin-connect) in the configuration/userlib/ directory of the Run distro.
For other, custom plugins, the process requires some Java and Spring Boot knowledge:
Since Camunda BPM Run is based on the Camunda Spring Boot Starter, you can create a Spring Boot module that wraps the custom Camunda plugin as a Spring Bean. Once you have that done, you can put the generated jar archive in the configuration/userlib/ directory of the Run distro. Since Spring Boot supports classpath scanning, the custom plugin will be discovered and loaded in the Process Engine.
Does this help?
Best,
Nikola
UPDATE:
The Spin plugin is actually included by default as in the other distros, so you can use it without any additional configuration.