Welcome, and thank you for your interest in contributing to PipeDream!
The main README.md and EXPERIMENTS.md contain instructions on how to build the dependencies, and run PipeDream on a few simple models.
You must sign a Contribution License Agreement (CLA) in order to have a PR merged. This a one-time requirement for Microsoft projects in GitHub. You can read more about Contribution License Agreements (CLA) on Wikipedia.
However, you don't have to do this up-front. You can simply clone, fork, and submit your pull-request as usual.
When your pull-request is created, it is classified by a CLA bot. If the change is trivial (i.e. you just fixed a typo) then the PR is labelled with cla-not-required. Otherwise, it's classified as cla-required. In that case, the system will also tell you how you can sign the CLA. Once you have signed a CLA, the current and all future pull-requests will be labelled as cla-signed.