Most browsers will download Unzip that file into wherever you like. This works with any browser on Windows, I don't have any Apple products, but I've been advised that Firefox works better there. On Android, I recommend Google's Chrome browser as it does the best job of providing proper HTML screen behaviour.

Unzip is built into the Windows explorer. If you are using Android, I recommend getting
   ES File Explorer
as it has .zip handling built in.

Once you have the product installed, load your browser and type the path into the command line.
To avoid further typing when starting APL, put the result into you favorites list.

If you need the on screen keyboard, press the word Keyboard at the top of the screen. To have it visible in subsequent sessions, press the word Config at the top of the screen, then:
   Change the Keyboard from Hidden to Visible
   Click the Save button

Be sure to learn the layout of the keyboard, because you must enter APL characters like foreign language glyphs.
transforms each time you type the second character. The above displays as
For Android users, I recommend getting the Hacker's Keyboard, as it provides a full keyboard.

After you've installed the product and opened a browser page to it, everything depends upon browser capabilities. Workspaces in lib 1 are in a file shipped with the product. You can only save workspaces without the leading 1. The workspaces you save are in local browser web storage, so if you switch browsers, you workspaces will not be available. The workspace 1 Host includes several verbs, including Backup which will download all of your web storage so that you can copy them into another browser or machine.

The )edit command allows the user to write multi-line functions. It includes a Choose File button that allows you to import files into your browser's web storage. This is is not a full fledged editor with all of the search and replace capabilities the modern user would expect. On Windows, I recommend Notepad++ and on Android I prefer Jota+. Both can be configured to view text using the APL font, "apl385.ttf" which is provided here.