Connecting to a free wireless hotspot exposes you to security risks. Most computers have a setting available allowing these connections to happen automatically, without notifying you.
While this ability isn’t usually enabled, it’s wise to check the settings of your phone, tablet, or computer so that you have to manually join networks in public.
Then verify with a store employee that you’re connecting to the correct network. Ask for the name of their hotspot. Hackers sometimes use generic names like Coffee Shop, Linksys, or AT&T Wireless to draw you into their hotspot.