A printed copy of the official instructions with the date read, the manager's identity and family details, a written decision on who applies and who pays, and a list of the questions the company needs answered about eligibility, tax and what happens if the manager leaves. USCIS supplies further forms and evidence instructions after the initial step.
Working from a dated reference
The official website states that applicants receive further instructions from USCIS after the initial application and fee, so the company cannot assemble a complete evidentiary file in advance the way it could for an L-1A petition. What it can do is prepare the facts that any later instruction will ask for: the manager's passport and civil documents, his employment chronology with the company, the corporate records showing the sponsoring entity, and the family members to be included. It should also record which version of the official instructions it relied on, because the framework is described in a dated source.
Do not reuse an EB-5 or L-1 file as if it were the Gold Card file; the categories ask different questions. Before any payment, obtain the company's own tax advice on a gift to a foreign treasury and the manager's advice on any personal consequence, since the immigration source addresses neither.