I followed every step in this tutorial:
https://www.digitalocean.com/community/tutorials/how-to-deploy-a-flask-application-on-an-ubuntu-vps

But when I try to access the site via IP I get the following error:
Not Found
The requested URL / was not found on this server.
Apache/2.4.18 (Ubuntu) Server at #MY IP# Port 80

Can you help me fix this?
Thank you very much