Zoom update

3 months ago I used IPAD to zoom call relatives, now I can't connect to a meeting. When I enter meeting code message says I need to update my zoom version to 5.8.6 or higher. When I choose update from "App Store" it won't complete, another message says it's not compatible with my IPAD. Updating to current Zoom version 5.12 says compatibility IOS 8.0 or higher. I have IOS 9.3.6. Why am I getting message when updating older Zoom version to newer version??