Ivona hasn't been available in Google Play since Amazon bought them. However, as far as I know the Ivona beta voices on Android were all still free apps until that time.
I still have an old copy of Ivona Amy UK English working on my Samsung Galaxy phone. This version has worked OK on Android v4, v5 and v7, but I don't know about v2. It's still the best Voice I own despite having paid for many other non-Ivona voices still for sale at Google Play.
I think if you google around you should be able to find the old free apk installation file. In case it helps, mine has a filename
Code:
IVONA Amy UK English beta-com.ivona.tts.voicebeta.eng.gbr.amy-1.6.23.422-422.apk