The CAF has a very good description here called the Beginners Guide to Aircraft Sponsorship.
There are many ways people can be an Aircraft Sponsor. This includes:
Aircraft Restoration
Aircraft Sponsorship
Aircraft / Pilot Sponsor
Restoration Sponsor
Supporting Sponsor
Click here to find out how you can Sponsor an Aircraft.
One requirement to become a CAF pilot is that they must become an Aircraft Sponsor on the airplane they will fly. After all, they are getting one of the biggest "Hands On" experiences and it is only fair that they participate in the cost.
However, being an Aircraft Sponsor does not automatically earn the right to fly a CAF airplane. Each pilot must demonstrate their capabilities and annually meet the CAF requirements. Also, all flights must support the CAF mission in some way. In other words, this is not an aircraft you can take on some pleasure trip as you please.
Here is the Aircraft Sponsorship Checklist (Rev July 2020) link to get and idea of what that form looks like.
However, before becoming a sponsor, start with Become a Pilot.
If you have any questions, feel free to ask the Operations Officer.