two questions regarding voucher conversion rate analysis

Hey there, I am completely new to Power BI Desktop. So it was hard to find a subject for that - sorry.

The initial situation

The data is from a membership-site we want to analyse. In this case it is about conversion rates for users signing up with a voucher.

For this need we have two tables with data:

• Table A - a list of voucher redemptions
  • Column "Redeemed on date/time"
  • Column "User-ID"
  • Column "voucher code"
• Table B - a list of transactions (payments) made by a user after using a voucher
  • Column A "Redeemed on date"
  • Column B "User-ID"
  • Column C "voucher code"
  • Column D "transaction date"
  • Column E "transaction value"
  • Column F "days between column A and column D"
  • Column G "60-day-conversion"
    • "Yes" if column F is between 1 and 60 days
    • "No" if not

The point that makes my two struggles so hard for me is that I think I have to work with the two values of "User-ID" and "voucher code", as this combination is guaranteed to be unique in table A. But not so in table B, as a user(-id) who used a special voucher code, could have done several payments later (with a monthly subscription for example), so the combination of "User-ID" and "voucher code" does exist several times in table B.

What I want to do next - and need your help for it

Two things (and my thoughts about it - but please be free to advise me any other direction):

1. I want to add a column "60-day-conversion" to table A (list of voucher redemptions) with the value of the column of the same name in table B (transactions) (column G) for the combination of a user-id and a voucher code.

So I think in pseudocode I would have to say in table A: Create a new column named "60-day-conversion" with the value from the first row in table B that has the same values in columns "User-ID" and "voucher code" as we have it in the corresponding fields in table A.

values as an example can be:

- 60-day-conversion | "Yes" or "No"

- User-ID | 685421

- voucher code | 30daysfree-summer2020

2. I want to add a column "total value" to table A (list of voucher redemptions) with the SUM of the values of the column "transaction value" of all the rows who have the same "user-id" and "voucher code" in table B as the unique row in table A.

I hope I have been able to explain what I need to do and need help for in an understandable way. Of course I am open to all ideas and approaches and available for questions from you.

Thank you very much!

Michael