Very creative puzzle mechanic I like a lot! Like others, I got frustrated because it's hard to see what number each digit is on. Something like a highlight on hover would make all the difference.
I feel like the first few levels could introduce the concepts a bit more gradually to make sure the player understands the rules before introducing real puzzles. Level one took me over a minute because my first thought was to select an 8 (each dot having its own zone is the most intuitive solution to me), but that wasn't an option. Similarly, in level 3 you introduce "Each zone must contain an equal number of dots", which got me stuck for a while too because the obvious example to me would be two zones with equal dots. The solution of one zone containing all dots feels like a next step to me, worthy of its own level.
But the fact I'm thinking this much about it means you've found a really neat puzzle mechanic! I'd love to see it developed further.