Open the job, then Financials, then Claims. Build the claim as usual. Save draft keeps it yours, to keep working on.
When it is done, go to Review, the last step. It ends on Mark ready for review and Save as draft. If approval is yours to do, it also shows Approve claim N. YourCA first saves any figure you typed and did not save.
You cannot mark a claim ready if it does not add up. The problems show against its lines. Fix those first.
When it is ready for review, you can still change it. It stays on the approver's list with the new figures. To get it off their list while you rework it, take it back.
If the approver sends it back, the claim is a draft again, with their reason at the top. Change what they asked, then mark it ready again.
