For players who have issues downloading the large mission file(s) for our servers, you can try downloading them from the below link instead and manually placing it in the correct folder. https://drive.google.com/drive/folders/1_YlQJDQoFH9Y99KSEE9IIjaOzNPNMKVv Once you have downloaded the .pbo file, it must be placed in the %localappdata%\Arma 3\MPMissionsCache directory. 
Your game should not be running when you do this.   If you need any assistance with this, create a support ticket on our Discord.