How can I get the data which are on an encrypted disk from a computer where the Safetica is not installed? I can imagine a situation when I would like to use the data from an external disk and would have to connect it to a computer other then my own.

On your external disk create an encrypted virtual disk with a desired size and then create a travellers disk from the existent virtual disk and choose it as a destination for the files needed to open it. Then, when you connect the disk to a computer, you will run the traveller.exe file and a window will pop up, where you will enter the password and afterwards it will behave as a normal windows disk.