Bitdefender is not the only free antivirus utility for the Mac. In fact, Bitdefender is free to to try, but it is fee-based. Quite frankly, I am very suspicious of software that downloads based on a single-click on a link on a webpage about a different product. The only purpose of Mac antivirus software is to disinfect Windows files that you receive on your Mac partition(s). If you handle all of your Windows files via your Windows installation, then antivirus software serves no useful purpose.
I strongly recommend that you forget about Bitdefender. On your Windows partition, install antivirus software that has a reputation for effectiveness. On your Mac partition(s), drop Bitdefender like a bad habit. If you want to use your Mac to disinfect Windows files, then install an antivirus utility that really is free and has a reputation for effectiveness and for not interfering with the operation of your computer.