MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
What you need to do is plug your pi into a monitor / TV and keyboard and log into the operating system or ssh - secure shell into your Pi from another computer - have a look at this. https://community.octoprint.org/t/finding-the-pis-ip-address/844
If you need ssh on a Windows PC, use this. https://www.chiark.greenend.org.uk/~sgtatham/putty/docs.html If you are using a Linux machine you can just ssh email@example.com or ssh pi@theip address, eg ssh firstname.lastname@example.org, or whatever your Octopi's IP address is. The user account is pi, the password is what you set it to when you installed Octopi. Then follow the instructions exactly in RPiMonitor's installation guide. You access the finished installation by http://192.168.1.21:8888. I wouldn't install anything else from the command line except RPiMonitor - I use a dedicated Pi like most people for Octopi - but I have about another seven or eight doing other jobs.