Some tips from an audi guy with similar struggles below. I've read different approaches suggesting motor oil, wd40, or silicone spray as lube. Others say absolutely NO lube for this application. I would certainly shy away from petroleum lubes or wd40, as those might swell the seal. A bit of silicone spray might be ok here.
https://www.audizine.com/forum/showt...ector-seal-Q-s
This one makes it look easy. Can you link to the amazon tool you bought?
another one. Says it helps to let them shrink overnight:
https://www.thedrive.com/guides-and-...r-seal-service