This Android App is one of my hobby projects. Even though I'm really happy that you want to support me, I would feel bad if I would accept donations. I have no running costs and enjoy working on this project. If you want to support the app, you are more than welcomed to help with translations and/or submit code contributions.
If you still want to donate some money, I ask you to rather support the Snapdrop Community via a donation to @RobinLinus, the inventor and maintainer of https://snapdrop.net. This app causes a not inconsiderable load on his Servers, so I ask you to support him instead.