I’m reasonably sure that the version of the mod downloaded from the updater is dated. Some of them are like that; I have to reinstall PK’s Rebalance myself every update.
Use this version of the mod
On the thread, click “https://github.com/chaosvolt/cdda-arcana-mod”, and it’ll take you to the Github page for it. Then press “Clone or download”, then “Download ZIP”.
The mod will be downloaded to wherever your default download directory is, most likely a folder titled “Downloads”, so go there.
In a different window, go to where your copy of Cataclysm is, open the “data” folder, then the “mods” folder.
Inside that is where all the mods are kept. Delete your current version of Arcana, which will be titled “Arcana”, or “cdda-arcana-mod-master”, depending on what version you have.
Go back to your default download directory, open the Arcana ZIP you downloaded, and extract “cdda-arcana-mod-master” to “mods”.
The old one must be deleted, or the game won’t know which version to use, since they’re both titled “Arcana and Magic Items”
I’m sorry if this seems patronizing; I’m not really sure how familiar you are with adding mods to the directories.
This will, unfortunately, need to be done every time you update the game via the updater (deleting and replacing Arcana that is, not redownloading Arcana every time the game updates) , so what I do is keep a copy of the “mods” folder with all of the mods, outside of the cataclysm directory, and every update I’ll delete the mods folder it adds, and copy mine back in its place.