Install git if you don't have it in your computer, then clone the project in your current directory with the following command line:
> git clone https://....
The project should be cloned at path ./samourai-wallet-android

To build an apk from these source codes, you will need to install the following dependencies of the project
- Java (JDK v17.x.x or later)
- Android SDK (v34.x.x or later).
And finally to accept the licenses necessary to use the Android SDK through the sdkmanager executable.

To avoid all this manual manipulation you can simply download Android Studio (https://developer.android.com/studio)
Open this project with Android Studio (by doing that you will get Java and Android SDK installed and you will have a prompt to accept the Android SDK licenses)

Now you can build your apk. Go to the project directory and start the build:

> cd samourai-wallet-android/
> ./gradlew clean assembleRelease

After this step you have produced an unsigned apk. Here is the path from your current directory:
./app/build/outputs/apk/production/release/app-production-release-unsigned.apk

[Optional] If you want to verify reproducibility ensure that the shasum of the unsigned apk is the same than communicated by Samourai.
To get the shasum of your apk:
> shasum -a 256 app/build/outputs/apk/production/release/app-production-release-unsigned.apk

Before to install the apk in your Android Phone you need to sign it with your keystore
If you don't have a keystore yet, create one with the keytool command. Here is and example of command line:
> keytool -genkeypair -alias sam-key -keyalg RSA -keysize 2048 -validity 10000 -keystore sam.jks

And finally sign the apk. The following command line will create signed apk named samourai-wallet.apk in your current directory:
> apksigner sign --ks sam.jks --ks-key-alias sam-key --in app/build/outputs/apk/production/release/app-production-release-unsigned.apk --out samourai-wallet.apk
apksigner is located in the build-tools folder of the Android SDK directory.

If you prefer to use Android Studio than command line to sign your apk, here are the instructions:
- Menu Build -> Generate Signed App Bundle / APK...
- Select APK, then click on "Next" button
- Fill "Key store path", "Key store password", "Key alias", "Key password" then click on "Next" button
- Select "productionRelease" as build variant ans finally click on "Create" button.

The signed apk is generated at folder ./app/production/release from the project directory.

Now you can install the signed apk in your Android Phone.