the modImplementations in readme.md don't work in projects, but jitpack did like so:
modImplementation 'com.github.NucleoidMC.DisguiseLib:disguiselib-fabric:1.0.3'

Although, since 1.0.4 (and in future releases) jitpack fails compilation with an older version of java, so this workaround no longer works, and the readme modImplementation also seems to fail.

You should just use nucleoid's maven. The library is there, so not sure why it failed https://maven.nucleoid.xyz/xyz/nucleoid/disguiselib-fabric/1.0.4/

If you don't need forge / common version, nucleoid maven is the way to go as Patbox mentioned.
I can implement a fix for jitpack though (I think TheEpicBlock mentioned it).