"Unexpected file format" appears when opening project

So I downloaded RPG Maker VX Ace Lite from Steam. I tried to open someone else's project that I downloaded, but whenever I do so it says "Unexpected file format". I can play the game just fine, but I can't open it. The file type is RPGVXAce Project, according to my PC.

I made my own project with VX Ace Lite, and it has the same file type as the project that I downloaded, and VX Ace Lite can open my project. Can you not open projects that other people made with the Lite version of VX Ace?

Lite has several limits, exactly because it is free and you need some reason to purchase the full version.
And you simply can't open a project that exceeds those limitations to protect them from being circumvented.

you can open other game projects as long as they are also done with the Lite version - some of those are linked here on the forum somewhere as there was a topic collecting links to Lite-Projects and other projects.

I suggest waiting until Ace is on sale on steam - several times a year it can be purchased for much less than 10$ through one or the other steam reseller.

Thanks.