Yes, I visited twice at the end of April.
The first day I had a timed entry they were sold out for the day so yes, get your tickets ahead of time. There were a number of people lined up for the opening after lunch and a staff member was walking down the line checking tickets. He was telling people they were sold out and there was no chance for entry that day unless they'd booked ahead. Line up before your time slot back in the left corner where the entrance to the crypt is. It's not well marked but once you are in past the ticket desks, go down the stairs to the AR area. You'll come back up when you are finished down there and can make a comfort stop or just go on up to the Mystic Lamb. (The bathrooms are new and nice, lol.)
I thought the Augmented Reality program was quite good. It is different than Virtual Reality in that you can see thru the glasses and see where you are going with the scenes projected on the glasses. It was very interesting and I learned a lot even though I'd seen the Mystic Lamb when I visited Ghent in 2019 and it was still being restored. It is chilly in the crypt. I went in April and it was chilly outside and even cooler inside.
When I was booking my entrance ticket I found the times on some days kind of weird so check and see what is showing for the day you are going. You first do the AR program which is down in the crypt and then doff your glasses (which fit over eyeglasses no problem) and go upstairs. The area behind the altar with a number of side chapels is blocked off from the rest of the church but is open to those who have paid entry. You can spend as much time as you want in this area and do note there is a Reubens painting in one of the chapels. I do recommend you bring binoculars if you travel with them. I loved looking closely at the flowers and other details, some of which were noted in the AR program.
This altarpiece is one of my favorite pieces of art. It is just so stunning to me and there is SO much detail! BTW, the giftshop up at the front of the cathedral (on the left side as you head to the exit) is pretty good too, lol!
Have you watched The Monuments Men? It's one of the pieces of art that was recovered by them from a salt mine in Austria.
I hope you enjoy it!