We use "puzzle mats" on our concrete floors - no problems. We purchased the better set from Great Mats (they're online) & recommend them - they're still going strong after 20 years & you can easily move them and store them. The type we bought is no longer made, but they have lots of other types. The less expensive (& less cushy) mats we have, we bought from Home Depot - they are harder, thinner but depending on your needs, may work okay - we now put these under the stationary bikes.
You can also do a forum search as flooring options has been discussed many times - Cathe's partner Chris has even posted a recommendation as I recall.