You are likely seeing a binary incompatibility of the plugin with the Gradle version in use. The class DynamicObject has been moved to the package org.gradle.internal.metaobject with Gradle 3.0. A similar issue was observed in another post.
The issue can be fixed by releasing a new version of the plugin using Gradle 3.0. Would you mind asking the plugin developer to release/publish a new version of the plugin?