I purchased “sport flooring” rubber tiles from the link above. Super easy to install, heavy duty and looks pretty good. Other than i got solid black which shows dirt like crazy. So i would advise one of the other color patterns. It seems to soak up noise and my trainer and treadmill have no slippage or bouncing on.
They will ship to your house or a local warehouse spot for pickup. I’m in Canada but the site refers to North American distribution and a warehouse in the US.