Well the error is appearing because the buddypress plugin is not installed .The error is coming from from buddydrive plugin which also requires buddypress plugin .
now what you have to do is to install the buddypress pluign manually via ftp .
https://codex.wordpress.org/Managing_Plugins
Setup and installation is not that much tough if you follow the exact steps as mentioned below :
1 . First of all make sure these php configuration on your server :
WP Memory Limit: 128 Mb
WP Max Upload Size: 32 MB
PHP Post Max Size: 32 MB
PHP Time Limit: 240
PHP Max Input Vars: 1000
PHP version 5.6 - 7.2 , (REcommended 7.0)
2 . Then download a fresh copy if wplms theme from themeforest .Now release 3.8.5 .
3 . follow this video for installation :
https://www.youtube.com/watch?v=ygsyaLFZnhs
Follow the one click installer .
Before one click installer please make sure that all the recommended plugins are installed and activated on site first .
There are three main plugin which wplms needs :
Buddypress , vibe course module , vibe customtypes .
If you are still facing any issues please do tell us or share all ftp and wp-admin details with theme uploaded on it ,we will do the installation .