I have recently installed docker which works without any errors. However, after executing ./Blockstack-for-Linux-v0.21.0.sh pull then ./Blockstack-for-Linux-v0.21.0.sh start and entering a passphrase I am taken to http://localhost:8888/auth?authRequest= which asks me to use a drop down menu and select “Home”. I do not have any drop down menu.
I was having trouble with the browser and I run Ubuntu 16.04, but not with Docker. The other things I did were: 1) do a hard reload of the browser; and 2) enter this command in terminal: blockstack api start. I hope it works for you.