Help me get games on this thing

I have tried reading the forum and every YouTube video I can find but I cannot get games on here. Ive been using FileZilla to help but it is not working.Im using macOS. I would like to find a good rom website but the internet is not helping and no website I find is giving me the game. I really want to play Pokemon Emerald. I know there is another forum question like this but it is too confusing. I would really appreciate any help I can get.

Vimm’s Lair is a fantastic resource, it has at least a nearly complete library of GBA games as well as myriad other consoles and handhelds. As to loading them on the system, what have you done through FileZilla? Is transferring the files not working, or can you even get connected?