Registration by invitation plugin

https://elgg.org/plugins/1142917
I know it's not easy and it has not been easy with those awesome developers. I pray it look easy for you all.
I am just a novice in website development but I have an idea in frag and drop website.
I came across Elgg for a long time and I see that it function is good but it's plugin is not completed.
I have written all plugin I will need for a particular website but right now, this plugin "Registration by Invitation" is an older version but I have no idea if it will work for v3.0 as I am planning on working on v3.0.
https://elgg.org/plugins/1142917
I know is not easy, can someone work on this plugin to make it compatible with v3.0?