It’s pretty much a formality at this point; she’s basically in: elizabethforma.com.
Glen Johnson from Political Intelligence explains what this means:
Federal law allows prospective candidates to “test the waters” for a possible candidacy by traveling, conducting polls, and performing research.
This can include forming an exploratory committee to formalize the arrangement, but not always.
While in this phase, candidates are allowed to raise a “reasonable” sum to conduct such activity, a vague measure, so long as they collection donations in accordance with federal contribution requirements.
They also are barred from speaking about themselves as a candidate.