Download the file "tensegrity.sage" and upload the file to your main project folder for SAGE. If you are using Cocalc the instructions are here: https://doc.cocalc.com/howto/upload.html
Then, you can load the file into your SAGE worksheet by executing the command load("tensegrity.sage"), which will load the Truss class into your session. Use the .sagews file to compute every SAGE example contained in the paper.
For numerical algebraic geometry calculations, including epsilon local rigidity, see the two .jl files.