Cannot install Server App on my NEW EX2

Got my new EX2 today, having just discovered Plex and finding that I can’t run the Plex server on my standard Mycloud. However, I cannot seem to download the app. I click install and it spends about 10 mins, getting to various percentages before crashing out with an error. I tried installing one of the other apps, and it worked a treat - in seconds. Is there something wrong with the download for Plexserver. Is there a way I can manually download and install it? what gives?

I have a similar problem installing the app. Only difference is my cloud dashboard confirms that the installation was successful. Then when I go to configure it asks me to install the Plex app. Been investigating/testing for a couple of weeks. Would be really interested in any potential solutions.