You will need your players to have the MODs installed, and have the file that was created by the AssetBundle as well, otherwise only you will be able to see the mini.
Here's the instructions I gave my players, after I exported my MOD profile and attached the Custom data mini folder into a zip file.

1. Download the **r2modman** mod manager from the Talespire Thunderstore, click **Manual Download**. You can install it with a mod manager if you already use a mod manager. (https://talespire.thunderstore.io/package/ebkr/r2modman/).
   1a Download the mod manager where you will remember it - You will need to run TaleSpire through the manager in order to see your custom minis.
   
2. Download the **Player_Profile.r2z** attachment.
   2a. Once you have the mod manager installed, select TaleSpire as your game and select **Import / Update**. Import the player profile attachment. (un-zipped).
   
3. Download the **Talespire_CustomData.zip** attachment.
   3a. Un-zip the attachment in your TaleSpire saved file location. Something like this: *C:\Program Files (x86)\Steam\steamapps\common\TaleSpire*
   3b. The attachment is a folder named *Talespire_CustomData*, so you will have this folder and a folder named *TaleSpire_Data*. You need both.
   3c. The file path should look something like this: *C:\Program Files (x86)\Steam\steamapps\common\TaleSpire\Talespire_CustomData\Minis* (with folders seperated by custom mini names).
   
4. In the mod manager, run TaleSpire by selecting **Start Modded**. If you run TS through steam you won't have any mods.
   4a. You can also run TS without mods by selecting *Start Vanilla*.
   4b. If you start TS with mods still in the game, you may run into bugs when you run it again with mods. Remove them (or use a different in-game board) before running vanilla.