It doesn't make any sound when I click the speaker icon. What's wrong with this?

Arabic language learning resources are few and far between. Thank you for building this. Do you know which Arabic this teaches? Koranic? Modern Standard? Levantine? Gulf?

Are the vocalisations of the letters synthetic?

Edit: If I wasn't acquainted with arabic script I'd probably not be able to make out the difference in vocalisation between some letters.

Saw a couple of words that (as far as I know) aren't "modern standard Arabic" is there any bias towards a dialect or another?

For a different method of learning Arabic (or several other languages), check out https://www.languagetransfer.org. It teaches Egyptian Arabic, explaining that the entire region knows this dialect because Egypt is the TV and movie hub of the Arabic world.

It's all audio (MP3s or streaming) and completely free, and (IMHO) the best language learning system out there. I have used it to learn Spanish, my sixth language and can't recommend it highly enough.