"Do you have to have a TD account to buy the pair?"

Don't know. The news release says: "underwriters... , led by Blackmont Capital Inc. and including TD Securities Inc". That sounds like there are a number of brokers involved. There usually are, with new issues.

At this time, the TDW New Issue page still shows the ECU offering as "open". So, I suspect, TD still has a supply. Normally the listing will flip to "closed" when it reaches the over-subscription stage.