The estimate does not start here. It is written in Xactimate or by your estimator, and it arrives as a document. What the system does is take that document apart into the numbers the claim will be paid in, and hold them on the claim where the invoices are raised.
Uploading an insurance estimate asks for the figures below, not just the file. The upload is blocked until the claim information is filled in, which sounds like friction until you have chased an estimate that belonged to no claim number.