UpdateUrl Field :
RaftModLoader fetch this link to know what is the latest available version of your mod, if the currently installed version is not equal to the version returned by this url it will say that the mod is outdated.
Our website offer this service with a nice automation system. Available on the following link once you have a mod slug.
https://www.raftmodding.com/api/v1/mods/
YOURMODSLUG
/version.txt