Prerequisites
You have a Safe setup via the web interface at app.safe.global/
The threshold is set to 2 or higher since you will be signing with the Safe Mobile app and execute the transaction with another owner wallet
How to confirm a transaction on mobile:
1. There needs to be a transaction initiated from the web interface.
2. On mobile, you should see a pending transaction waiting for confirmations.
3. After opening that transaction, you will be able to confirm it.
4. After confirming, it can be executed via the web interface.