You'll have to look up what its "FreeSync range" is. There is a lowest frequency/refresh rate you have to stay above to avoid picture tearing. So, if the FreeSync range is 80-144 Hz you'll have to keep it between those two to keep a smooth tear-free image. The top end you usually avoid going above by setting a max rendering refresh rate on your graphics card, the bottom end is mostly decided by your card's performance.
Edit: Google said its range is 48-144 Hz. So, that's the minimum you'll have to keep above.