DR6: How to sideload an .apk file to the Android 12 mobile device (via download)

One-time setup to allow this type of installation (i.e. if you've already done this, you don't need to do it again):

Settings
Apps
Special App Access
Install unknown apps
Chrome
enable "Allow from this source"

Install the file:

In Chrome, browse to the link to the desired apk file.
Choose where to download, tap Download button
When complete, tap Open to go there.
You should see your apk file. Tap it.
If you have an earlier version of the app, there is a message "Do you want to update this app?" Tap Update to install.
Tap Done or Open.