Here's the article: https://www.spurstalk.com/spurs-big-board-3-2024-nba-draft/

Obviously the Spurs took Castle so it's notable that they refused to talk about one of their top targets (even after hyping up Devin Carter from the same workout with Castle). They've been interested in Risacher for a while considering RC Buford and Peter Holt both scouted him in person. Sheppard is undersized but based on intangibles/personality and the need for shooting I can see it, and some sources were certain Sheppard wouldn't drop past the Spurs.

That leaves Knecht. Draft Insider Woo from ESPN did mention the Spurs were one team with "strong interest" in him a few weeks ago.(https://www.reddit.com/r/NBA_Draft/comments/1daazxn/givony_updated_big_board_with_intel/)

Jeff McDonald from Express-News also has this pre-draft quote from Brian Wright where he said: “We broke the (franchise) record for (total) 3-pointers, but then percentage-wise we’re towards the bottom end of the league, right? So I think you obviously want to add shooting.” so a shooter was clearly an identified need. Listing the two targets for this as Sheppard and Knecht in the same article is probably not a coincidence. (https://www.expressnews.com/sports/spurs/article/nba-draft-preview-picks-19539233.php)

Knecht at 8 would explain why Spurs were willing to trade out. They might like him but weren't thrilled to take him so high considering his age and defensive flaws. I bet they were trying to trade down and maybe get him for better pick value but nothing worked out until the Timberwolves called.