I installed the app from the Play store on Android. I have emailed the app developer to see if I get a response back. I have seen though that there are other people saying that their RM Pro+ is not working with it.
I suspect that Broadlink have made some changes to the device - possibly to specifically stop 3rd party integration, and there are actually 2 variations on the RM Pro+. Unfortunately, I think that this latest one is the only model of the Broadlink RM Pro that you can get now (unless there are old stocks), even if you specifically order the RM Pro (without the plus).
I did also email Broadlink support and was told the following:
Dear Customer,
Thanks for your interesting of BroadLink products!Pls kindly note the device of RM pro+ can help work with Alexa on TV control through the IHC app, but not support the e-control app with it, and the RM Bridge is not from BroadLink, so we don’t how to use it, thanks!
*We will support the Alexa to work with the AC and RF code in the future, now i also don’t have the datetime, but once the skill is okay, we will publish to you, so pls just waiting, thanks!