What is the Wendler 5/3/1 log application, how does it work?

According to the introduction of SaraSoft, Wendler 5/3/1 log is a Health & Fitness app on the Android platform. There is currently a 17.5 version released on Mar 01, 2020, you can see the details below.

No more fiddling around with printed spreadsheets at the gym. This 531 app will help to manage your 531 workout program.
This app generates the 5 3 1 workout program based on your current lifts.
A detailed overview of cycles including sets, reps and weights are calculated.

★★★This app is not affiliated with Mr. Wendler(creator of the program). Please buy his book(s) to fully utilize the ideas behind 531! ★★★

This is a trial version.
In-app purchase allows to remove the restrictions and allow to log unlimited number of Wendler cycles.

Full working trial for 1 Wendler 531 cycle :
★ Calculates one rep max (IRM) based on your current lifts
★ Configurable training max percentage
★ Configurable number of cycles
★ Configurable weekly workout order
★ Warm-up sets included
★ Boring but BIG sets included
★ 16 predefined assistance exercises
★ Possibility to add your own assistance exercises
★ Cycles overview with estimated and achieved one rep max
★ Progress indication of workouts in cycle overview
★ Plates calculator shows the plates to load
★ Rest timer
★ CSV export via email, google drive
★ 2, 3 and 4 day split workout templates.

Pro version )
Logging of:
★ Joker sets
★ Another main lift as Boring But Big
★ First set last ( AMRAP and custom variation )
★ 13 week challenge
★ Editing of completed workouts
★ Configurable warm-up percentages
★ Configurable Boring but big percentages
★ Separate timer values for warm up, main lift, boring but big and first set last
★ Separate timer values for accessory lifts
★ 3/5/1 and 8/6/3 rep schemes added
★ Configurable warm up reps
★ Support for subtracting collar weight