Answer:
Automatic backup copies are stored in the working directory in a folder with the same name as the model you have processed. This folder contains all the files created when entering the model data and performing the calculation, including the backup file Position.bak (see Image 01).
Copy the Position.bak file to another folder and rename it "Model.rf5" or "Model.rs8". Thus, you can open the file with RFEM or RSTAB.
The Position.bak file is automatically deleted when you quit the program correctly. However, when you open RFEM/RSTAB after the program crash, a message appears asking whether the backup file should be opened again.