Available on the following storefronts:
Note: this is the original version included with Capcom Arcade Stadium, being offered to all Steam users.
Street Fighter II improved many of the concepts introduced in the first game, including the use of special command-based moves, a combo system, a six-button configuration, and a wider selection of playable characters, each with a unique fighting style.
Credit to Wakrak, PhatTofu & g12345567 for alerting me to its availability on PS4, Xbox & Switch.
Is it for Macbooks with Steam as well?