Welcome @HairyRichardThey are all relevant questions, there is...

Welcome @HairyRichard

They are all relevant questions, there is definitely a lack of information and the info we do have is sometimes not clearly stated.
I'll have a crack at helping but I'd recommend reading the 2019 and 2020 investor presso's, the comments on previous FTC threads (it's pretty quiet here, there's not many to go thru) and if you have the time, the 2020 full year report.

The 2020 Investor Pres states 'annual transaction volume has reached over CNY 1 trillion (2020 financial year)' which roughly equates to 3Bil/day. Bear in mind this was stated in September, only half way thru FTC's financial year which, you are correct, starts in March. The banks that signed up prior to March 2019 are only charged a capped fixed fee, not the 2-3BP. The 2019 Investor Pres stated 1.5M/day was processed on a capped fee while 200mil/day was processed on a 2-3BP fee. With GTV now having grown to 3Bil/day, we don't know what percentage is capped v 2-3BP. I also haven't been able to find how long the capped contracts last for but it would be hoped that when they expire, they will then be moved onto the 2-3BP

Post #: 48078165 this post discusses the capped fixed fee revenue v the 2-3BP revenue. I'd also recommend slide 7 in the 2019 investor pres. However a good explanation of why some banks are on the capped basis is actually in this months quarterly under 'Operation background and forward thinking'.

Post #: 46026857 this post is a quote from the company regarding the delay in collection of receipts. Yes there is a delay. Up to 12 months

The 80% figure in the quarterly is referring to accounts receivable, not revenue. Section 16 in the Sept 2020 HY report states Trade receivables 18M, however comparing this to receivables in March 2020 of 15.1M and in Sept 2019 of 10.4M prior to COVID kicking off, you can see that accounts receivable is a normal part of business and likely what they are referring to is a portion of this 18M was from earlier in the year and they have collected 80% of it. How big was the portion? Can't be sure. If they had no business growth from Sept 2019's 10.4M to Sept 2020's 18.0M, you might guess the portion delayed due to COVID to be 7.6M and from this you could guess that 80% of 7.6M = 6.1M of this months 22M receipts was collected. However, by all accounts the business is growing so you would expect receivables to increase normally which would decrease the size of this portion.

Of course, this is just my opinion