This 36 year-old has a few thoughts to share with you.
1) Starting Strength is a good book to reference for performing the movements, even if Rippetoe can be a bit verbose at times. I think he wrote 40+ pages on how to squat. I think you can cover that without 40 pages, but he's the author. I really found the photographs and diagrams helpful when I was learning how to squat, deadlift and press barbells.
2) Starting Strength is generally considered a good beginner program, but I'm not sure how far you'd get on it as a 50 year-old vegan. Maybe you'd get very far, maybe you'll stall fast. No way to know unless you try.
3) I would buy the original 5/3/1 2nd edition. I think Wendler covers how to squat in a page or two. This book more than any other has shaped my personal approach to lifting, and I think it is a very sensible way for a serious lifter of any age to go about training with barbells. I still have not found a more concise explanation of what you need to do to succeed with barbells. If I had to recommend a specific program, it would be 5/3/1 with the Triumvirate template from the 2nd edition book.
4) Don't rule out bodybuilding without barbells. I've always trained with them, but others have had a lot of success without ever loading their spine up with a lot of weight. There are many paths to success.
5) Don't kid yourself about the level of caloric intake required to lay down new muscle tissue. Plenty of vegans have had success with lifting, but this choice places you at an undeniable handicap. Make sure your expectations are tempered appropriately. Most importantly, make sure you are eating for success. I'd highly recommend reading up on successful vegan lifters and make note of their methods.
That's whats kicking around my head this a.m. Good luck to you!