[HammerThrow]

You might be able to use spray insulating foam to fill the gaps from inside. It might be a bit of a mess and you will probably have to go around the outside rim to trim any foam that oozed out.

Indeed, I will make a mess but I will try to keep it to a minimum. I'm most concerned about keeping insects out so I will have to do it.
Thank you for the suggestion!

 

[HammerThrow]

It depends on if they bought the insulation package. Many metal buildings are unheated

In this case, think of it as a good thing, it wont rust as fast being off the concrete a little.

expending foam is one way, you could get painters caulk from Sherwin WIlliams, 850 will work good, spend the extra money and get a dripless caulk gun too, and while there, open a home owners account with SW.

No, I didn't buy an insulation package. My biggest concern is keeping it dry and keeping insects out. The painters caulk might be easier for me to control🤔.
I will definitely get a dripless caulk gun as well. I won't need the homeowners account though. I work for a big box home improvement center😎.

Thanks for the info!