This is in one word BRILLIANT! super smooth login experience from the get go. authentication is a pain to develop and even more so if you add biometrics to the mix. so this deal will save you a lot of headache and $$$$ on developers. Furthermore if you have any experience with working with e.g. users of saas you will know that the number one issue is that they tend to forget passwords, A LOT. so going passwordless is the future and using it in your apps will save you oodles of time resetting passwords and will make your users super happy.
When they say you can use it with any app they are not kidding. everything from react to webflow. I cannot beleive that this deal is on appsumo and I for one am SO pleased to have found it!