The default install is now 64 bit as you have discovered.
We haven't distributed a 32 bit db for at least 2 years (possibly longer), 90% of our corporate users are on O365 subs and are on 64 bit office.
Most DB should be easily converted, the main stumbling block is the use of depreciated Active-X add-ons.
There are some differences if you use a lot of API calls to change pointer types, they are fairly well documented.