I clicked SCAN NOW botton for MACKEEPER, but DIDN'T DOWNLOAD..

Hello, I have an iMac. and I tried to download a music mp3 file.

Suddenly, there was a notification saying my mac was in dangerous so I should SCAN NOW.

I clicked the "SCAN NOW" botton, then there was a blue bar showing like processing something.

Then it said I should download MACKEEPER.

It was suspicious, so I stopped and didn't download at all.

So, i'm worried that if my iMac is in danger right now

because i clicked the SCAN NOW botton and there was a blue ber looked like something was installed.

you know the blue bar that goes from left to right.

Even though I didn't download the MACKEEPER, Do you think my information was stolen?

Or some bad virus has been installed on my iMAC?

What should I do, now??

Please help me...T.T