I looked at the description and while I do not believe I have use for the app, I installed it anyways.
The summary of what it does on the App Store is pretty clear so I thought I could try it for the purpose of giving you feedback.
It was a very frustrating experience and I am not sure where to start.
Navigation is non standard. In fact, I could not leave the app, I had to close it from the task manager. I suggest you use the normal menus, everyone is familiar with that, and give an "exit" choice at the bottom, or trap the back button.
I do not know where to get the srt files from. Some guidance would help. Once one downloads the srt files, where should they be located? (Which folder?)
How do you synchronize the text to the movie? There is a drop down list with numbers and "slower" at the bottom. What do the numbers correspond to? I suspect they adjust the speed but on my phone, clicking on any of these choices made no difference in the speed.
There are buttons at the top of the screen. They are so small that only a small portion of two letters are displayed, impossible to tell what they do. If this app is designed for a tablet only, please say so.
Honestly this needs work. It may work for you but ask someone near you with no prior experience to install it and use it so that you can see for yourself the difficulties a normal user would experience.