Install it to the n8n root folder. This is the node_modules folder on the same level of n8n and n8n-core. This differs when you used the -g flag on n8n initial installation. From there do:
npm install @digital-boss/n8n-nodes-odoo-trigger
Navigate to desired folder, create a package json and install n8n like so:
cd /var/www/vhosts/
mkdir my-n8n && cd my-n8n
npm init --yes
npm install n8n
npm install @digital-boss/n8n-nodes-odoo-trigger
Directly:
n8n
Plesk or C-Panel:
node /var/www/vhosts/n8n/bin/n8n