There are aluminum filler metals available for the SMAW process. They are welded using DC. Be warned, the welds can be rather ugly in appearance and they are consumed at a rapid rate. With a little practice the welders should be able to make welds that are reasonably decent looking. Remember to clean the joins immediately before striking the arc.
The flux is highly corrosive, so it must be completely removed at the conclusion of welding. Chip, wire brush, and flush with warm water to ensure its complete removal.
I have some aluminum welds made nearly 50 years ago made with SMAW. Once ground smooth, no one will know what they looked like in their as-welded state. Ty are still intact and serving their original purpose.
Best regards - Al