Sumifs using week ending date

This is for an internal cash flow report.

The week ending date is based on weekdays only, i.e. if the 01 April '19 is a Monday (let's call this week 1), the week ending date will be the 05/04/19 (Friday), rather than 07/04/19 (Sunday).

Any planned payment with a date of, say, 06/04/19 will be included in week 2, week ending 12/04/19.

Please see example workbook with brief comments on the issue I am having. Hopefully makes sense.

Any help appreciated. Thanks.