@Jenna great idea !! Thank you !!
Check out Teachers pay Teachers. There are a lot of potty training resources for students with autism- you could adapt them for your home!
My autistic son was non verbal at the time he was potty trained and he learned from modeling behavior with his younger brother. Watching potty shows also helped and we did about a week of Poop camp where we would pretty much lock ourselves in the master and soley focus on potty training. After the very first time he went on his own, it just clicked. I hope you have had success since then.
If communication is an issue, can he point to pictures? You could have a toilet picture in every room. When you ask if he needs to go, point to the picture. Hopefully, he will learn to point to the picture when he needs to go. Also, don't get upset or make a big deal with an accident. Here is a good resource. https://www.autismspeaks.org/expert-opinion/seven-toilet-training-tips-help-nonverbal-kids-autism