Moving into a new apartment that has a Friedrich WSE Wall Sleeve. Height 16 3/4 in, Width 27 in, Depth 16 3/4 in I'm thinking about getting the GE AJCM08AWH (Seems to be like the only through the wall ac with wifi that is somewhat affordable.) Dimensions:15 5/8 H x 26 W x 21 13/16 D Would this be too tight of a fit and I'd be better off getting a 24" W one instead? Or is it's fine? IDK I was thinking inside circulation? I've only ever had window air conditioners.

Here's a photo of the sleeve. Is the board that's behind the grill supposed to be removed, or would I just slide in the air conditioner in as is? Just wondering if installing it something I can do myself or should I hire someone. Thanks in advance for any advice

They have the sleeve through the window