So I play Ruby storm and last night I had a match against an opponent playing 4c Omnath control. On game 1 he had a [Teferi, Time Raveler out] and when I had my [Ral, Monsoon Mage] ult ready I asked him if he wanted me to play it out or if he was willing to conceed to go to game 2(I showed him grapeshot and it was clear that I had enough spells for the win). He stated that Teferi prevents storm triggers from working because it only allows you to cast at sorcery speed.

Now from what I thought Storm doesn't actually have you cast the spells, it just puts them on the stack directly. Am I wrong or was my opponent wrong here?

Overall it didn't imapct the match much because I was able to win through getting a [static prison] on his Teferi but I'm just curious for future games where it might be an issue.