Website with Client Portal for Accoutancy firm

I want a website for our accounatncy firm , for which we need Client portal where client can register themselves after approval every clinet will have own page where they can can see their details which we will update from back panel , like clinet name address , important numbers , etc. other part should show important upcoming dates when our clients tax returns will be due and client will receivied 2 reminders before 2 months and 1 month for thoese dead line. 3rd part client can download documents which we will share with them like 2019 tax return every year should have different catagory . 4th if we required documents from client we can create document request with documents name from back panel and it will apear in client portal as request with upload button so client can upload documents ,thier should be option create more than 1 upload request. 5th our service invoice client can pay online or can see balance for their service how much they paid we can adjust it from back panel. i am going to upload a sketch which is not final but for your understanding i did some work.