just purchased update, unity issues

Hi, long time user of you're previous audio plugin, decided to upgrade, and I imported it into my project and i'm getting all kinds of errors.

Can you help me resolve this?

Some errors:

Assets\Plugins\Editor\RelationsInspector\BackendUtils\BackendUtil.cs(6,26): error CS0234: The type or namespace name 'Extensions' does not exist in the namespace 'RelationsInspector' (are you missing an assembly reference?)
Assets\Plugins\Editor\RelationsInspector\BackendUtils\DrawUtil.cs(3,26): error CS0234: The type or namespace name 'Extensions' does not exist in the namespace 'RelationsInspector' (are you missing an assembly reference?)
Assets\Plugins\Editor\RelationsInspector\BackendUtils\ScriptableObjectBackendToolbar.cs(3,26): error CS0234: The type or namespace name 'Extensions' does not exist in the namespace 'RelationsInspector' (are you missing an assembly reference?)
Assets\Plugins\Editor\RelationsInspector\BackendUtils\MinimalBackend.cs(11,47): error CS0246: The type or namespace name 'IGraphBackend<,>' could not be found (are you missing a using directive or an assembly reference?)
Assets\Plugins\Editor\RelationsInspector\Backends\HierarchyExample\SceneHierarchyBackend.cs(14,39): error CS0246: The type or namespace name 'IGraphBackend<,>' could not be found (are you missing a using directive or an assembly reference?)
Assets\Plugins\Editor\RelationsInspector\BackendUtils\MinimalBackend.cs(17,30): error CS0246: The type or namespace name 'GetAPI' could not be found (are you missing a using directive or an assembly reference?)
Assets\Plugins\Editor\RelationsInspector\Backends\AutoBackend\RIAutoBackend.cs(13,31): error CS0246: The type or namespace name 'GetAPI' could not be found (are you missing a using directive or an assembly reference?)

There's a bunch more but all in the same RelationsInspector

The project was running just before I updated and imported.

Thanks
k