To install this mod you need the following
19 plus (obviously) https://pizza-tower-19-plus.itch.io/pizza-tower-19-plus-sage-2024-demo
Deltapatcher https://github.com/marco-calautti/DeltaPatcher/releases/tag/v3.1.5

All you need to do is open deltapatcher, select the original file as the data.win in your 19 plus installation, and the xdelta patch as the patch included in this folder. If you do that then it should work!

Keep in mind this mod is for the most recent patch (The Farewell SAGE Patch) so if you aren't on that version it most likely won't patch correctly.
ALSO, it apparently only patches correctly if you get 19 plus from the itch download (I have absolutely no clue why this is the case) so be sure you got it from there.
There's not much I can do to help if it for some reason just refuses to patch so you'll have to ask a friend for the data.win in that case.

Enjoy your lap 3 experience and have fun!