There is probably conflicting information out there on what video conferencing product was used. However, this article that I pulled from CNBC indicates that MSFT Teams was the go-to primary line of communication:
https://www.cnbc.com/2020/04/27/nfl-draft-proves-it-can-work…
“There were no discernible glitches or delays in the draft process. Subbing out face-to-face contact with the Microsoft Teams communication and collaboration platform, the NFL was able to prove it’s just like any other business. In the face of this crisis, it too can work from home.”
As well as this portion of the article:
"Microsoft Teams served as the primary line of communication between the NFL and its franchises, as well as how official picks were submitted to the league (some teams chose to also use the Microsoft technology for their “virtual war rooms”).
To the credit of IT employees around the league, “everything ran smoothly,” an NFL spokesman told CNBC. The first two days of the draft were all-time ratings highs, he said."