mounting the mesh server involves first installing the nodejs software package
or
Then I recommend the pm2 module to keep your server running even after the raspberry pi reboots
Then download the software from GitHub - nootropicdesign/lora-mesh: LoRa mesh networking (either 'git clone' or download the zip file and unzip it in a subdirectory on your Raspberry pi)
Then cd to the mesh-server directory and start with 'pm2 start app.js'
Modifying it to talk to your sensors over serial will be more difficult. Start with https://www.npmjs.com/package/raspi-serial or serialport - npm