Step 1: Go to teltonika.lt, find your device and go to the "downloads" section below the image of the device.
Step 2: Click "Teltonika Configurator (EN)"
Step 3: If you have any FMB device, go to the "For FMB series" click the "Download .zip" button on the latest version. If you have an FMB640, go to the "For FMB640" section and do the same. If you have a TMT250, go to "For TMT250".
Step 4: Find the .zip file you downloaded, extract it anywhere.
Step 5: Go to the folder you extracted and find "Teltonika.Configurator".
Step 6: Run it. It should work with no installation.
Also do not forget to download COM port drivers from the same product page. They are needed for the Configurator to understand your connected device. Just repeat Step 1 and click "FMB PC Drivers". Then open the .zip file, run the .exe file and click "Next" to go through the installer.