Developing a fully functional emulator is a massive time-consuming project. With donations you can show your appreciation for this effort and at the same time support the development.
Check out our Patreon page if you are interested in supporting us!
If you haven't heard of Patreon before here is the gist: It's like your usual crowdfunding platform but instead of pledging once, you choose an fixed amount that you are willing to give per month. Based on how much you donate there are even some rewards you can get in return. It's practically risk free because you can cancel your subscription at any time.