Write the following command in your terminal:

adb install [-rtsdg] <file>

Note that you have to pass a file that is on your computer and not on your device.

If you append -r at the end, then any existing conflicting apks will be overwritten. Otherwise, the command will quit with an error.

-g will immediately grant all runtime permissions.

-d allows version code downgrade (only appliable on debuggable packages).

Use -s to install the application on the external SD card.

-t will allow to use test applications.