This method works for the other versions of the game aswell, v0.2.0 and later versions will not require the original SCP: Containment Breach game to be installed.
Download the game files
To install v0.1.1 of SCP: Containment Breach Nine-Tailed Fox mod, you must go to it's ModDB page: https://www.moddb.com/mods/scpntf. Then go to the Files and install Nine Tailed Fox Mod v0.1, then also install SCP: CB Nine Tailed Fox Mod v0.1.1 (PATCH).
Now you have to install the Containment Breach vanilla game, you have to either install v1.2.2 or v1.2.4 (you can also install v1.2.3 if you can find it), the download link is: https://www.indiedb.com/games/scp-containment-breach/downloads or https://undertowgames.com/forum/viewtopic.php?t=4358
Extract/move the files
To do this, you must download WinRaR, the link is: https://rarlab.com/download.htm. You must check your PC settings to see whether or not you should download WinRaR 32-bit or 64-bit.
Once you have downloaded WinRaR, open up all the files that you installed and make a new folder in your desktop (you can do this by right-clicking your mouse and selecting 'new' then clicking 'Folder'), you can name the new folder whatever you want. Now you have to start extracting the files, starting with SCP: Containment Breach v1.2.2/1.2.4 by highlighting all the files in the WinRaR folder and moving them to the new folder. Do the same for SCP CB NTF Mod v0.1.0 and then for SCP CB NTF Mod v0.1.1. When you move the files of v0.1.1 of the NTF mod, a message will pop up saying that some files have the same name, click on replace files (this is because v0.1.1 is a patch to fix some bugs).
4GB Patch tool (optional)
This next step is completely optional and is not necessary, but it reduces Memory Access Violations, to download the patch tool, the link is: https://ntcore.com/?page_id=371. Once you've downloaded it, run the program and go to 'This PC/Desktop' in your files. Now, go find the name of the folder in which you extracted the game files and select 'SCP - CB - Nine Tailed Fox Mod' inside the files then a message should pop up saying that the patch was successful.
Run the game
To run the mod, double click on 'SCP - CB - Nine Tailed Fox Mod' not 'SCP - Containment Breach' otherwise you'll be playing the vanilla SCP Containment Breach game.
If the game says that you are missing DLLs then search them up online and download them then move it to the game directory (the place where 'SCP - CB - Nine Tailed Fox Mod' is located), if you can't find them then your best bet is to thoroughly read through this again or look at the video link and reinstall the mod. You can search for missing DLLs here: https://www.dllme.com/
A reason for if you have missing DLLs is that you extracted the Nine-Tailed Fox mod into the folder before SCP: Containment Breach v1.2.2/1.2.4