Strapi on my Coolify

Thanks for this guide! But I don´t get why I should start the destination path with /app. In addition, I have a configuration with ssd + hdd and I was wondering how I should link just the heavy files in my hdd. I think I need a way to link just /public to an internal folder such as /mnt/hdd/uploads and for the other directories just let coolify doing its job setting a persistent volume. Do you have any suggestion?