MSA has very few resources so I decided to share a resource list! (I got all of these from an Arabic discord server by the way: Let's Learn Arabic)
For the core basics of Arabic learning (Lessons in Arabic)
Teaches all Arabic grammar in great detail (http://allthearabicyouneverlearnedthefirsttimearound.com/)
Italki, great for finding teachers (Sign in - italki)
Anki, one of the best flashcard apps (https://apps.ankiweb.net/)
For learning the Arabic alphabet (http://arabicquick.com/learn_arabic_alphabet/)
Really good short stories in Arabic (https://youtube.com/playlist?list=PL7RpCYE5gLKF3Wus9QmIXHuy4p81lpaVA)
Textbooks
Mastering Arabic 1 and 2 https://www.amazon.co.uk/Mastering-Arabic-Paperback-Jane-Wightwick/dp/1137380446
A Focus on Contemporary Arabic (https://www.amazon.co.uk/Focus-Contemporary-Arabic-Conversations-Speakers/dp/0300224044/ref=sr_1_1?dchild=1&keywords=a+focus+on+contemporary+arabic&qid=1628185907&s=books&sr=1-1)
Easy Arabic Reader, great for beginner to intermediate level (https://www.amazon.com/Easy-Arabic-Reader-Jane-Wightwick/dp/0071754024)
Colloquial Arabic of Egypt, by the same people who made Mastering Arabic
(https://www.amazon.co.uk/gp/product/B014KS6IV2/ref=dbs_a_def_rwt_bibl_vppi_i1)
Glossika - Great if you don’t lose motivation after a week