In such cases you should contact plugin devloper they can give you best support.
In most cases this is caused by code degradation (not being updated with UE4 API changes) as author forgot to update it, in that case and if plugin is abendent you need ot fix the code yourself. Figure out when plugin was stop being maintained UE4 version wise, download that version of UE4, try to build, see if there any deprecation warnings (UE4 is quite good on those and usally prints out what you need to do to fix it), if there is fix them, get next UE4 version and do this again and again until you get to latest version, you can risk skipping version if you want to speed up a process, but some deprecation warnings are just for 1 version some have tendency to stay for very very long.