1.You have to download the mod itself from Gamejolt:https://gamejolt.com/games/UndertaleBnP/574044 and unpack the mod itself separately

2.In the mod folder, you need to find a program, you definitely need this program called Deltapatcher, run the program and offer you the Original file: this is data.win (I advise you to make a copy of the file of a separate folder for updating the mod on a note told you) and the second button is necessary for a mod called
Xdelta patch: utbnp_v4.2 that's what you need to patch there is even a Mac OS called Mac_to_Win for mac users

3.when you do, replace all the files, even the ost and if there normal are 2 exe files UNDERTALEBNP.exe change the name to UNDERTALE.EXE and you will work perfectly through the launch of STEAM
4.launch the game and you can play there by the way, there is a decoration in the files for the incentive, an improvement like Undertale on the background of the game and a cap for it
5. how to enable the Discord mode function to show others the status of your character, etc. in the game settings, you need to turn Internet mode on proof of:

6.The screenshots show how to do this