In Steam settings choose betas, then select 1.10.8 from the list. It will start to download. You do not need a code.

I meant a version of the Mod,cause its on 1.11.4

I want the Mod version for 1.10.8

Here you go: Legacy version updated less often if your save is no longer compatible:
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2361995178

Here is what worked best for me:

1) Follow the first post -- use Beta feature and Steam to Install the 1.10.8 version.
2) Download the mod from the "previous versions" tab of this top-mods page: Total War 1.10.8 under Previous Versions[top-mods.com] and copy the contents to this folder: Documents\Paradox Interactive\Hearts of Iron IV\mod.

Unlike the "legacy" link above, this one has not had combat widths altered, It should be the actual version that was compatible with 1.10.8.

i thought it was compatible with 1.11.4?