Wordpress-functionality-plugin is no longer in dropbox location

I’ve been ignoring my theme development for a while (try a couple of years!) and since the last time I worked on it, I have rebuilt my PC software from a clean install. So I’m back on a bit of a learning curve.

When I installed my theme (which was based on the starter theme) the text part of my posts is not showing, either when I copy the theme from a backup or generate from an up-to-date Pinegrow. So I’m thinking plugin difference, and I tried the install, and chose the functionality plugin and got this error

I’m not convinced that this is my problem, but the chances are that I will need this. How do I get that going?

Thanks,
David