If you already find K-9 Mail application as in picture, go to Chapter Continue

Open application K-9 Mail

Install K-9 Mail

If you don't find F-Droid application, then you need to prepare FOSS for Android/F-Droid before.

Open F-Droid apps manager

Tap on search area

Enter k-9

Tap on K-9 Mail (only this simple caption)

Tap Install

Package download can take some time

Review new application permissions and tap Next until you see the Install button

Confirm to install this application: tap Install

Installation can take some time...

Once application is installed, tap Run

Continue

Follow screenshot indications