On Travis for Education, Travis VM's do not have any support for LaTeX. And it is also not possible to use sudo on these VM's, so simply installing the right packages using apt-get is not going to work.
Obviously, it is ridiculous that Travis for Education is not supporting the full range of possibilities that Travis Pro has. However, complaining about it doesn't really help that much. Hence, I created a quick and dirty solution that solves this problem.
Practically, the solution is to install TeX Live manually. In a directory that the normal travis user can always write to.
Unfortunately, texlive uses an installer, which takes some commands, or a profile. The profiles are relatively complicated to use for installation, and I wanted to get something working quickly, so I simply pipe the commands into the installer.
d -- Go into directory edit
1 -- Edit the main directory
~/texlive -- set the main directory
r -- Return to the main menu
s -- Choose a scheme
c -- Choose the scheme 'c' (small scheme (basic + xetex, metapost, a few languages))
r -- Return to the main menu
i -- Start installation
Add tlmgr install <package1> <package2> as an installation command to your .travis.yml to install extra packages.
It could be very benificial for the build time to choose a very minimal scheme and to install only the packages that we really need.
One of the things that I found while testing, is that there definitely is some throttling going on while downloading packages. Sometimes the installation takes few minutes, but sometimes it takes about 30 minutes.