No worries! You don't need to include a ZIP of art or anything like that. Just credit me in game and tell the user that the art is licensed to you under the CC-BY-SA 4.0 International license. You can copy this sample text if it helps:
"Thank you for playing [Insert Name of Game]. The art for [Insert Name of Game] is sourced from #NotZelda Overhead Adventure Tiles by LUNARSIGNALS and licensed under the Creative Commons Attribution-ShareAlike 4.0 International license."
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To be specific, the "Share Alike" (SA) clause means that if you make derivative work of the CC-BY-SA artwork, then you should share this derivative work under a similar license. The general understanding is that a game using this artwork is not a derivative work, so in this case you only need to give attribution (BY). If you create new art assets based on this artwork though, then you should share it under a similar license. Your own art assets which are not derived from #NotZelda are not affected by this license, so they can stay proprietary.