The screenshots are from the Windows version but you have the same screens on Linux.
If you already have an account on your device, click on your account name (not the gear) on the top-right-corner, then click on “Add an account”. You should then be redirected to the screenshots I’ve shared to create a new account.
Oh? I thought SRTP was end-to-end encryption, so it only had to do with the end software used? I guess I don’t understand SRTP. Do you know a good resource I can learn from?