If someone offers you their source code, they are unlikely to offer you support to go with it. By the time you figure out what is going on in their code, resolve any undocumented or implicit external dependencies, get rid of extraneous features, add features that you need, you will end up investing a lot of time. You may be better off just writing it from scratch using reference code from Microchip available through various reference designs on their website. And all of that is assuming that the code they give you actually works n the first place.
---55p