Could not find a version of package ... matching "stable"

[delovelady]

I tried to install this per the instruction:

composer require splitbrain/remarkable-api

I received this error:

Could not find a version of package splitbrain/remarkable-api matching your minimum-stability (stable). Require it with an explicit version constraint allowing its desired stability.

Since I am fairly new to Composer, I do not know how to correct for this, or what "Require it with an explicit version constraint allowing its desired stability" means.

Are there updated instructions? Running this on rPi bookworm.