Hello Vidarr ,
Thanks for writing us.
If you just wish to encrypt and decrypt a file using AxCrypt being offline, you can do it.
After establishing your credentials and login in desktop app, click on file menu at righthand side corner, click on option and select always offline. You can use this application in offline mode always.
Please try and let us know if you still face any issue. You can write us at support@axcrypt.net.