Yes 
By default Atlas will block external access so you need to whitelist the IP address that you want to talk to it from. Out of the box, it’s pretty friendly in terms of working out your current IP you’re accessing the UI from and adding that, which will probably be your dev machine.
If you access it from another location, say a hosting provider then you need to tell Atlas about what IP range will be making connections and add either an individual IP address or the range that it could come from.
If you search the forums you’ll see a number of posts about setting up the whitelist but the key thing will be working out the IP address your hosting provider is using to talk to Atlas.
You could for testing add the address listing in the message, 0.0.0.0/0 which will allow any client on the internet to talk to your Atlas instance. If you do this make sure your security is locked down and only do it briefly for testing. (strong passwords etc)