When donors send money to the platform, Taproots expects donors will be buying seeds for a project with that money. Thus, the cash is ultimately transferred to creators and project owners, who withdraw it in order to launch or expand their project. This is one of the main purposes of the platform.
Donors retain their seeds. Ideally, creators and project owners will continue to provide value to the donors, by rewarding donors with tangible benefits to seed owners.
Precisely what those benefits are depends on the Project Owner and the nature of the project. A few examples might be: a complimentary subscription to their service, a free copy of their book, inclusion in a membership club, free downloads, etc., etc.
While the money is held by Taproots, Taproots will endeavor to keep it as liquid as possible in order to satisfy the likely withdrawal of the funds by creators almost as soon as it is deposited. Monies that have not been spent on seeds that remain in user accounts will be managed conservatively by the Taproots organization and kept separate from business operations.