The path(which the file is there) does not has necessary(write) access for the user. That’s the reason you are getting the exception.
I think, you are using the older version of AxCrypt app. I suggest you to use AxCrypt 2.x for more features and great usage.
Unfortunately, if you do not know the password for an AxCrypt-encrypted file you cannot open it, even if you can sign in to the account. This is by design, it’s just this situation that AxCrypt is made for and it works like this even if you actually are the original owner of the file.
If you think you almost know the password, we have simple software allowing you to try to find your password, and you can download the most recent version from https://account.axcrypt.net/Download/AxBruteForce.exe and read of how to use it at https://www.axcrypt.net/axcrypt-brute-force/ . Please note that we cannot provide support beyond this.
If you do not remember the password to your account, you can always reset it. This is not a way to recover encrypted files! It’s only to allow you to sign in to the AxCrypt app and web.