This is the installation file for Decal v18.104.22.168 a.k.a. v3.0. This is the newest version of Decal to have been released.
Although Decal does seem to work with the A.C. ACEmulator server. And although AC Tool & Companion do seem to work with Decal when connecting to a A.C. ACEmulator server. Do expect any support for Decal in any way beyond the setting up Decal and AC Tool & Companion when connecting to a A.C. ACEmulator server.
As the developers of Decal had abandoned the project years ago, prior to Asheron's Call was closed down. And I have not found any forums, Discord channel or any website. Where there is any discussion of, let alone any support for, Decal.
The following Tutorial well show you how to properly install the Asheron's Call game and Decal to play on a emulated server:
How to setup Asheron's Call to play on a emulated server