No, you cannot use your own floor cleaner in the Braava jet m6. You must only use the official Braava jet Hard Floor Cleaning Solution in the tank. Other substances like vinegar, generic cleaners, or soap can clog the Precision Jet Spray nozzle and the cleaning tank, and may damage the robot or void its warranty.
To use the cleaning solution, add 6 capfuls of it to the empty tank first, then fill the tank completely with water. You can also mop with just plain water by skipping the solution entirely.
Even when using the official solution, you should rinse the tank regularly with warm water to prevent residue or odors. Never pre-soak the mopping pads before starting a job; the robot is designed to dampen them itself.