Firefox Send can be used without signing up. The limitations are 1 GB instead of 2.5 GB, a maximum of 1 download instead of 100 downloads, and a maximum of 1 day instead of 7 days. So it's still useful in certain circumstances.

Why not MiDrive Transfer? I haven't heard of it and don't know how reputable it is. And is it in beta? So it could be buggy?