150mm is unusually big. See if it says how many cubic metres per hour it extracts. You can get 150mm duct, but it is not so common.
You can also get a 150mm to 100mm adaptor, but the instructions ought to say what size of duct you need, it may vary with length. If you can duct it straight through the wall with a short duct, it will have the easiest flow. Look for a cowl vent with a single non-return flap under a weather hood to go on the outside of the wall.
You can get a core drill from a tool hire shop that will make a very neat hole. I like to pack the cavity with loft insulation mineral wool before pushing the duct in and mortaring the edges, because any existing cavity fill will tend to be disturbed.
You can also get a 150mm to 100mm adaptor, but the instructions ought to say what size of duct you need, it may vary with length. If you can duct it straight through the wall with a short duct, it will have the easiest flow. Look for a cowl vent with a single non-return flap under a weather hood to go on the outside of the wall.
You can get a core drill from a tool hire shop that will make a very neat hole. I like to pack the cavity with loft insulation mineral wool before pushing the duct in and mortaring the edges, because any existing cavity fill will tend to be disturbed.