Now we have the root of the problem.
What do you mean by blocking access to your computer (avast isn't a firewall), do you mean it is alerting, e.g. detecting it as infected ?
If so then we should confirm if the detection is good or false, if false, exclude it from scans send the file for analysis and correction of the VPS. I will show how to do this if that is what it is.
First I have never seen this pop-up so I can't say for certain that it is avast's, assuming that it is. If you didn't set a password have you tried simply clicking OK without entering anything ?
Don't try disabling vial the task manager the self-defence module will block that, right click the avast 'a' icon, select Stop On-Access Protection, remember to start when you are done.