Print ASA without enclosure
According to MatterHackers, Simplify3D, and 3D Insider an enclosure is not necessary but highly recommended as ASA, like ABS, is susceptible to drafts and can warp. A heated bed is necessary (somewhere between 90-110 °C), and little-to-no cooling fan used. The enclosure helps ensure adhesion and a consistent temperature. ASA also has fumes and an enclosure can help contain unwanted smells.

MattHackers has a video (Step 4 in the link) on making an enclosure with some kind of plastic sheeting or trash bag (I didn't watch it). There are videos on YouTube on using cheap Ikea side tables and acrylic sheets to make an enclosure if you want a more permanent solution.