the steps are:
- download the files from git https://github.com/muchasuerte/ha-besmart/archive/main.zip
- make a folder under HA dir e.g. /home/homeassistant/.homeassistant/custom_components/
- copy extract the main.zip and copy the folder custom_components/besmart under /home/homeassistant/.homeassistant/custom_components/
I’m using HA 0.113 which version are you using?