There are two different APIs to get player match overview - one that returns numeric representations of how many matches a player has participated in, and another that returns individual match details in paginated format (that is - request some, then move the “cursor” a few records forward, then request more matches from that specific starting point, repeating until you hit the end). Using the endpoint that returns matches in a paginated format, get all match IDs until exhaustion (no more matches left to page through). That being said, for players that have quite a few matches played the computation might take some time as it’s done in sequenced batches of twenty five records per API call - for someone with 10,000 matches that would mean a whole 400 API calls to get the full list.