PHP errors when installed

All files where uploaded and I added all template edits as well as the "3.5 only" edits.

I am getting errors when I click on any forum. Here they are:

Warning: Unknown(OMITTED/forum/plugins/vbplaza_threadbit_display.php): failed to open stream: No such file or directory in /forumdisplay.php(941) : eval()'d code on line 2

Warning: (null)(): Failed opening 'OMITTED/forum/plugins/vbplaza_threadbit_display.php' for inclusion (include_path='.:/usr/local/lib/php') in /forumdisplay.php(941) : eval()'d code on line 2

Warning: Unknown(OMITTED/forum/plugins/vbplaza_postbit_start.php): failed to open stream: No such file or directory in /includes/class_postbit.php(251) : eval()'d code on line 2

Warning: (null)(): Failed opening 'OMITTED/forum/plugins/vbplaza_showthread_start.php' for inclusion (include_path='.:/usr/local/lib/php') in /showthread.php(97) : eval()'d code on line 2

I think those are the bulk of it all.

Can someone tell me how to fix this (in laymans terms) please?

Thanks