I’d check out Free League’s 5e-based Lord of the Ring’s Role-Playing Game. (The new edition of Adventures in Middle Earth). It blends 5e and Middle Earth very well.
Website here.
All these AL adventures have five 1-hour mini-missions, that are good for a short time time slot and for beginning DMs:
DDEX1-1 Defiance in Phlan
DDEX2-1 City of Danger
DDEX3-1 Harried in Hillsfar
DDAL04-1 Suits of the Mists
DDAL05-1 Treasures of the Broken Hoard
DDAL07-01 A City on the Edge...
If you’re a Luddite, maybe Owlbear Rodeo? Won’t give a lot of functionality, but does the basic job of tokens on a map very well. And is free. Neither Foundry or Fantasy Grounds are easy to learn, and while playing in Roll20 has a low barrier to entry, DMing does not.