I think that the first time I saw Tapatalk application used to login into one forum was on taxi or Uber forum. At first, I thought it was a feature only available to the administrator or site owner but it was later that I found out it's just an application which anyone can easily and equally use as well to login into a forum where it's enabled to be used.
Personally, I haven't made use of Tapatalk application to login into any forum till now but I have made use of other social media sites which I have an account on to login into several forums I wanted to participate in. One good thing about using social media sites to login into a forum is that it would make you registration on the site very easy and without stress for you. It's most my Twitter account that I have used for such purposes.