The register feature doesn't even work. I got the following plain text email:

  Username: xxx

  To set your password, visit the following address:

The mentioned link was missing :(

(weird that an PDF was attached too with the same text, and no link)

They could have at least added the binary to the Github release: https://github.com/MrKepzie/Natron/releases/tag/2.0.5 The software looks interesting, but I cannot try it even out.