Don't bother applying. They (like all tech companies these days) don't respect your time. Recruiter round (showed up late) hiring manager round take home assessment ghosted on takehome with subsequent messages to the recruiter all ignored
You need to build a small app per their directions.
The following metrics were computed from 5 interview experiences for the BILL Staff Software Engineer role in United States.
BILL's interview process for their Staff Software Engineer roles in the United States is extremely selective, failing the vast majority of engineers.
Candidates reported having very negative feelings for BILL's Staff Software Engineer interview process in United States.