Because "PS2 Save Builder" is a specific Windows application and there isn't a direct, official Android port with the same name, most users looking for this guide are trying to used by the PS2 Classics emulator on Android (AetherSX2 / NetherSX2).

The Ultimate Guide to PS2 Save Builder for Android: Managing Your AetherSX2 Saves

provide downloads for various utilities, including converters that might run via browser-based scripts

Think of it this way: you build the save on PC, then “deliver” it to your Android emulator.

Choose the memory card slot (Slot 1 or Slot 2) to import the data.