vRealize Orchestrator plugin issues

I've recently installed Vrealise Orchestrator, and it is working nicely with Vsphere authentication etc.

I'm hitting a wall attempting to install the Unity and Powerscale plugins.

I keep getting "Error! cannot parse plugin file"

I'm running Vcenter 7.0.4, Vro 8.7.0, and the latest plugins from the DellEMC page.

I have tried installing them both from my laptop, and from a couple of seperate servers inside the DC on the same infra as the vRO and Vcenter VMs.

I've downloaded the plugins both on the laptop and the server, and also via my home broadband (in case the work system was messing with it).

Same results every time.  I'd be grateful of any suggestions to try.

Is there any logs I can check for a more specific error, or is it possible to unarchive the vmoapp file and install manually?

Regards

Gary