Thank you for your message. One of the updates in the R302 release is changing the XMDS schema to v6:
This change means that R302 cannot be used with version 2 CMS instances. I can see there is a typo in the release post which will be corrected shortly. it is recommended to use the player version that matches your CMS version, in this case that would be R258. Thank you for pointing this out and our apologies for the confusion.