How important are SAT scores for IB students?

In the IBDP, I have a 42 predicted with a 766 in HL Physics, Maths and Chemistry and 777 in SLs - including English L&L. However, even after doing the SAT 3 times and days and nights practicing, my highest score is 1450 (660 RW and 790 Math) and subject test scores are worse - I’m applying for engineering

How heavily do schools weigh SAT scores for IB students?

Do SATs scores still need to be really high when the student can do those subjects fine in IB? (to get into the top - let’s say - 30 US colleges)

The same as for every other applicant.

Or higher if you are an international applicant. So no, you don’t get a pass for being IBDP, and given that the acceptance rate for intl applicants is about half the overall rate at some of these colleges, your stats should be as good, or higher, than the typical applicant.

Having said that, all these schools evaluate holistically, and stats are just one part of the package.