Need help with an ACS Error

Yo
I recently decided I was gonna make a library for my commonly used ACS functions and whatnot. So I cracked open a few guides and did that. Few hours later I can finally play my maps with the functions - now stored in the library - executing properly, but i'm still getting an error in the compiler about my imported library. The error I'm getting is an invalid declarator error on line 1 of my imported library because the compiler only shows "ACS" as the contents of the library. Extremely new to this stuff so I'm just wondering whats going on and what I can do to fix it, because I can't imagine this is how its supposed to be lol.
Using Slade3 for resource editing, GZdoom builder for wad making.
got an imgur album here with pictures I took from slade and gzdoom builder if that helps: https://imgur.com/a/aBHhr
I recently decided I was gonna make a library for my commonly used ACS functions and whatnot. So I cracked open a few guides and did that. Few hours later I can finally play my maps with the functions - now stored in the library - executing properly, but i'm still getting an error in the compiler about my imported library. The error I'm getting is an invalid declarator error on line 1 of my imported library because the compiler only shows "ACS" as the contents of the library. Extremely new to this stuff so I'm just wondering whats going on and what I can do to fix it, because I can't imagine this is how its supposed to be lol.
Using Slade3 for resource editing, GZdoom builder for wad making.
got an imgur album here with pictures I took from slade and gzdoom builder if that helps: https://imgur.com/a/aBHhr