Bats in the attic of a home with a metal roof are a lot more difficult than if it were a traditional shingled roof. The main reason is the repairs. If it were a shingled roof, you could apply sealant along the edge of the ridge cap preventing entry whether it was a roofing sealant or a metal edge called ridge guard. In the case of a metal roof, you would have to first determine if the ridge cap is used for venting.
If it used for venting the heat out of the attic space, then you will need to install a vented closure which does cost much more in the materials. You could also use ridge guard as well, but regardless it must be sealed in a way that allows hot air to escape the roof but not let bats in.
If it is not used for venting but is indeed missing the required closures, then you would install those. A metal roof has many openings not just at the ridge cap but also along the edges where again closures should be installed. The corners of a metal roof almost never have a closure installed because there really isn’t a closure made for each inside and outside closure forcing people to make their own either from metal or foam. Bats take advantage of these openings, and since all of the inside and outside corners will need to be sealed this does create a much larger expense than a shingle roof which typically fit tighter eliminating the gaps.
The worst bat job would be a log cabin with a metal roof so if you have one of those you will need to hire an expert without a doubt.