Everything works fine with 4.21, but if you build from code you will be missing an #include, and will also have several depreciated warnings, I have updated this plugin to remove those warnings and bring this plugin up to date with 4.21 (Only code, I have not provided any binaries)
this is still the best dialogue plugin I have found out there… just follow the tutorials for now, but I plan on adding a few options for my game, so I might continue to update this plugin.