Android Guide:
Step 1: Install f-droid, click here

Step 2: Install Conversations app from F-droid

Step 3: Open Conversations and follow the steps in these images:

Step 3.1


Step 3.2


Step 3.3
In step 3.3, pick any username you want. Change username to whatever you want as your username, just make sure it ends with @freesoftware.se like in the picture.


Step 4 (Optional): Click this link to join the newcomers group chat: Link