There are lots of caveats when making your own DataStore module - so many, in fact, that some of them are not even documented on the official Roblox API (And you certainly won’t have strangers on the forums list the entirety of them for you 
). I highly advise you to at the very least explore modules that were created by the community to get the grip of what it truly takes to make an efficient module - as Eryn, an Adopt Me software engineer, says: “Don’t make code that has already been written before if you want to be an efficient developer”.
There are already enough forum threads to do research on your own. Good luck.