Normally, one would expect a broker to know these things and tell you.

From a US perspective, ACRFF is a "pink sheet" or "over the counter" stock. You should be able to buy it through any US brokerage, but trading volume is typically low -- meaning that liquidity is lower and pricing usually less favourable (to you) than if you were trading on a European exchange.

https://finance.yahoo.com/quote/ACRFF
https://www.otcmarkets.com/stock/ACRFF/overview

Some (many) US brokerages will let you buy and sell on European exchanges. I held AC.PA in a Fidelity account a few years ago, for example. The trading costs were higher than for securities traded in the US, but not prohibitive.