Malwarebytes

I have the free version installed, however it is not required asssuming you practice safe computing such as:

• Never download from a site you do not know or trust.
• Do not fall for phishing scams or other types of scams as Apple describes in https://support.apple.com/en-us/HT204759
• Do not use a torrent to download software you did not pay for.
• Follow Apple's advice in https://support.apple.com/guide/mac-help/protect-your-mac-from-malware-mh40596/mac

Your welcome.

should I allow Malwarebytes access to my hard drive to do a full scan

You can if you would like, it will not harm anything.