Boot Time Scan?

Hello, I’ve just installed Avast on my girlfriends Mac but despite clearly having issues with pop-ups and strange website mis-direction the scans don’t seem to be picking up on anything.

Is there a boot time scan like in the windows? I’ve found that is typically more likely to detect virus’s and trojans.

Any idea on how to make that work or any suggestions on how to clean a Mac?

Thanks,

but despite clearly having issues with pop-ups and strange website mis-direction the scans don't seem to be picking up on anything.
Looks as it may be full of crapware

Try Malwarebytes for Mac https://www.malwarebytes.org/antimalware/mac/

Maybe these tools can help you to find active malware/Crapware on your Mac:

https://objective-see.com/products.html

Especially TaskExplorer, Dynamic Hijack Scanner and KnockKnock may help you out.