Here is what someone from Quebec wrote to my request:
”All the information is on the site, which indeed doesn’t say much. The program should come out by the end of spring or early July, but it is the first post-COVID edition so you know how things can be. On a normal edition, there are free activities and paying ones on designated sites. You need to buy a medallion - $15 maybe - to access the paid sites. The streets are indeed packed, but they usually are in QC in the summer. The Hop On Hop Off avoids the pedestrian streets, but know that Old Quebec is pretty compact (about a square mile) so it is pretty walkable. If you don’t feel like climbing the steps between Lower and Upper Town, there’s the funicular (I think it’s $4 now).”